DP-777 SE

Unrivalled.

DP-777 SE

Unrivalled audio.

Audio redefined.

As the CD slides into the player and the first notes ring out through your speakers, the first pluck of the string and soft vocal should hit your ears with pure, undiluted pleasure

If it doesn’t, we have the answer. The DP-777 Digital Processor.

Unrivalled HD audio.

AMR believe no stone should be left unturned in delivering high-definition audio.

That’s why we loaded the DP-777 with a Gemini Digital Engine, which includes not one but two distinct chipsets:

  • The High-Definition 32-Bit DAC – to produce the ultimate audio from HD recordings
  • The Classic Multibit 16-Bit DAC – to harness the best audio from CDs

These give the DP-777 the edge over the competition with sound that’s clean, crisp and without equal.

The tech spec.

The DP-777 also includes the following AMR exclusive components:

  • Zero Jitter Mode – to eliminate distortion and jitter from your speakers
  • Global Master Timing – which picks up 28 million frequencies and eliminates jitter at its source
This is HD audio at the peak of its powers.

Unleash real potential.

If you’re looking for pitch-perfect instrumentals and clear, natural vocals, then the DP-777 will strip away jitter and noise to unleash the real potential of your CD collection.

Think you’ve heard everything?

Think again.

Features

Gemini Digital Engine(GDE)®

Sonically speaking, the textbook implementation of HD DACs leaves a lot to be desired. This justified the decision to continue with the same innovative and comprehensive digital approach as the CD-777 and the CD-77 before that.

AMR’s HD Gemini Digital Engine is an ingenious implementation of two separate DACs; a HD 32-Bit DAC and a Classic 16-Bit DAC with Field Programmable Gate Array (FPGA) and Digital Signal Processing (DSP) to handle all core digital duties, including the memory buffer and managing the signal processing. AMR has in reality, created custom-built DAC chipsets to its exacting specifications which is akin to programming many discrete logic IC’s worth of circuit boards onto one chip. This approach is technically arduous and time-consuming, but is soon justified upon listening to just the first few notes of music from the DP-777.

Organic Digital Algorithm incorporating SMART®

At the top of AMR’s unique Digital Filter Algorithms is the “Organic Algorithm” which incorporates SMART®: (S)oft roll-off, (M)inimum-phase, (A)podising, (R)ingless, (T)echnology. This is AMR’s technical expertise at its very best where it has developed an original and comprehensive digital algorithm to address the sources of “digital ringing”; pre-ringing & post-ring in the recordings and in the playback of the DAC. Being the only manufacturer in the world with the “Organic” filter, in conjunction with the rest of the far-reaching digital and analogue implementation, the DP-777 is the first High-Definition DAC in the world that truly makes music to stir the soul.

OptiSampleHD®

AMR appreciates that “no one sound fits all” and that the highest quality of music reproduction is to ensure the original signal bit/sample rate is maintained all the way through. Hence, AMR developed the DP-777 with OptiSample® via both its High Definition and Classic Multibit DACs to ensure the original recording is preserved end-to-end.

The DP-777’s High Definition DAC offers: Organic, MP Listen, Apodising 808, and Traditional digital algorithm modes.

Under the DP-777’s Classic Digital DAC, the DP-777 offers: Bit-Perfect I and Bit-Perfect II filter modes.

All are all user-selectable, via the remote control and offer different perspectives on the sound but most important of all, reproduce the original recording to the highest degree.

Global Master Timing®/Intelligent Memory System®

Before the arrival of the DP-777, the issue of solving jitter introduced via SPDIF using a Phase Locked Loop (PLL) Clock recovery was seen as sufficient. However, this analogue “solution” to a digital problem is woefully inadequate yet is not even commonplace.

AMR’s Global Master Timing (GMT)/Intelligent Memory System (IMS) represent a total “out of the box” systematic digital solution that solves the digital SPDIF jitter issue once and for all. The Intelligent Memory System holds a large number of complete audio samples, so it may completely absorb a large amount of variation (jitter and drift) in the incoming signal, while still sending out data at a fixed and precise clock rate, regardless of variations in the incoming clock.

Central to the GMT clock system is an ultra-low jitter, quartz-driven clock system capable of producing over 28 million different frequencies. When engaged, the GMT system intelligently and dynamically controls the clock that drives the DAC chips and takes the data out of the memory buffer. The GMT Clock is set to precisely match the principal frequency of the incoming clock with a precision of better than 0.001Hz. Hence, if the frequency shifts from 192,000.002Hz to 192,000.003Hz over a period of minutes (drift) which is the minimum to be meaningful, the GMT clock will intelligently and precisely track the change.

Once the GMT clock has correctly calculated the incoming clock, the rate of updating the DAC’s clock with the minimal 0.001Hz step (~0.004ppm accuracy) step is at most, once every few minutes or less. As a result, the DAC clock is completely decoupled from the source and completely stable.

With the GMT clock that drives the DAC Chips and to clock the data out of the memory buffer at the same exact frequency as the incoming clock, there is nil jitter in the source clock, as there is no physical PLL link between the source clock and the clock driving the DAC Chips.

The GMT System is not a secondary PLL as used in some cases and some DACs since the late 1990’s, but an entirely new concept. Instead, GMT is a system that will completely block jitter and only react to compensate any slow drift in the clock source or to adapt to a change in sample rate.

The GMT Zero Jitter mode is available for all digital inputs including the USB input and is the new clock standard reference for the digital audio world.

Asynchronous 24/192 USB Input

The DP-777’s Asynchronous USB 24/192 means native and future-proofed playback on OSX and Windows.

Asynchronous USB 24/192 uses USB Audio Class 2.0 in Asynchronous Mode and is fully compatible with USB 2.0 and USB 3.0. It should be keenly stressed that USB Audio Class 2.0 should not be confused with USB 2.0. USB Audio Class 2.0 is required to support sample rates above 96kHz (that is, high-definition music). AMR is one of a handful of companies to have brought such a standard to market following the industry definition of the USB Audio standard.

Most USB DACs do not follow the global USB Audio standard and hence will require drivers for all PCs (including Macs, Linux) which may be unavailable and must be supplied by the manufacturer into perpetuity, for each new operating system.

By comparison, USB Audio Class 2.0 is built into Mac OSX and many versions of Linux and supported by Microsoft on Windows and is set to be recognised as an industry-wide standard to achieve native “plug & play” support in all future operating systems.

Asynchronous mode means the clocks are on the DAC side and the PC is synchronised to that stable clock. Compare this to the common way of USB audio workings where the DAC attempts to synchronise to the PC using a jitter inducing PLL to follow all the PC’s clock changes, be they caused by software directly modulating the clock or indirect clock modulation due to the varying processor loads (this is called software-induced jitter).

By combining our Asynchronous USB Audio Class 2.0 connection with the Global Master Timing/Intelligent Memory System we are not only delivering future-proof, cutting-edge computer connectivity with virtually nil jitter, but we also completely remove the jitter of the clocks.

Crucially, the USB signal is completely decoupled (i.e. isolated) from the DP-777. So any power supply noise, RFI and ground noise from the PC is not able to enter and contaminate neither the DP-777 nor its signal.

Bit Perfection®

Presently, virtually all CD players and DACs are NOT “Bit-Perfect”. Such machines are only “Bit-Perfect” at the input interface section. None are truly “Bit-Perfect” end-to-end because the use of traditional digital filters will artificially manipulate the signal and the sonically damaging artefacts that result is readily detected by the human hear. Any DAC using oversampling (to any frequency) or asynchronous upsampling is NOT Bit-Perfect.

The DP-777 is one of a select few able to deliver a true, “Bit-Perfect” signal all the way through to the output as it preserves the signal integrity from the input (SPDIF/USB) right through to the pure valve analogue output stage.

HD SPDIF Inputs with Valve Digital input technology

The Compact Disk standard was never conceived with the notion of distinctly separate transport and DAC sections but once this became so, SPDIF was adopted as the method to link the two together. However, SPDIF is an analogue transmission system that uses what was originally a video signal format to transmit a digital system. Clearly, this is not an elegant solution as the SPDIF clock and signal are transmitted together as if the red, blue and green signals for a television were cobbled into a single run.

At AMR, to overcome this set of essentially analogue problems we devised a completely analogue solution. AMR’s proprietary Valve Digital input technology (VDi) is a world’s first: it is the use of the NOS 6N11 (high-speed valve operating into the 100MHz region) in a zero feedback circuit derived from military radar technology to re-establish the clean waveform of the original incoming signal from the two HD SPDIF Inputs.

Firstly, this ensures that even if the input SPDIF signal has an incorrect output level or poor waveform, the SPDIF input receiver will have a clean and perfect SPDIF signal to lock onto.

Secondly, as all SPDIF receivers use Schmitt Trigger input circuitry, the receiver will create a glitch noise at the trigger point, this noise travels back into the SPDIF cable, returning to the source component. It is this errant noise that is at least in part responsible for the major differences between SPDIF cables and sources in the input system of common DACs. As the HD-VDi isolates the SPDIF receiver from the outside world, HD-VDi eliminates the detrimental effect caused by this noise once and for all.

The DP-777’s HD SPDIF inputs employ a NOS valve input circuit for everything all the way up to the 24/192 high-definition standard. The result is clearly visible on an oscilloscope as the SPDIF signal is restored back to its perfect wave form. This input ensures the “right note at the right time” to give the music the “life” that is missing from all other DACs.

OptiValve®

AMR believes that having the ultimate in digital execution would count for little if the analogue section was not just as committed. Hence, the analogue section of the DP-777 utilises AMR’s OptiValve® analogue stage with zero negative feedback and NOS 6H1n-EV valves. The “EV” designation represents the premium version of this valve. Being a double triode per channel design; in the DP-777, one half amplifies and the other buffers. Rectification and filtering in the DP-777 uses zero-noise Schottky diodes with additional noise filtering, an electronic inductor and a virtual battery design. The analogue stage of the DP-777 is identical in concept and function to that of the CD-77. With no operational amplifiers or solid-state devices, this is a major factor behind the DP-777’s organic and “vinyl-like” sonic performance that will embarrass many a high-end DAC.

Direct-Coupled/Buffered Analogue Volume Control®

The DP-777’s Direct-Coupled, Buffered Analogue Volume Control (AVC) system is AMR’s ground-up analogue volume control system that is both transparent yet dynamic across the whole 71-step range. The AVC gives a completely noiseless change of volume and virtually nil distortion but with more steps and finer resolution that betters even the best stepped attenuators. The AVC functions as a series of near perfect switches, with no ageing, no degradation and no wear. It is finely adjustable in 1dB steps but the beauty is the extreme transparency that is second only to the famous transformer volume control (TVC) approach first developed by Western Electric at the turn of the century. Partnered with a fitting power amplifier such as the AM-77 or AM-777 (in Power Amplifier mode), the signal path does not get any shorter, rendering the music virtually palpable.

OptiTrans®

AMR’s expertise in specialised transformer design for audio use has led to the development of transformers with individual windings that offer the sonic benefit of individual transformers without the space demands. Again, AMR has shunned the mainstream (and more cost-effective) approach to the use “off the shelf” transformers, preferring to have its own dedicated transformers, with multiple layers of shielding built-in, hand-wound and hand-made. Power supply is an integral part of circuit design and AMR’s steadfast approach has ensured the highest possible quality of music performance.

The Finest, Cherry-Picked Components

Underpinning the design of each and every AMR component is the use of premium components which were selected after careful evaluation and exhaustive listening. These include AMR silver leaf capacitors, Sanyo Oscon capacitors, precision wire wound resistors, 70um gold plated military-grade printed circuit boards, AMR’s own German-made premium film and foil capacitors, power supply polypropylene film Music Capacitors and zero-noise Schottky rectifiers. We positively encourage a closer inspection of the DP-777’s internal componentry.

Specifications

Operation modes High-Definition 32-Bit DAC
Organic 44.1/48/88.2/96/176.4/192KHz
Apodising 808 44.1/48kHz
MP Listen 44.1/48/88.2/96/176.4/192KHz
Traditional 44.1/48/88.2/96/176.4/192KHz
Classic 16-Bit Multibit DAC
Bit-Perfect I; no digital or analogue filter
Bit-Perfect II; no digital filter, sinc(x) analogue filter
Digital Audio Inputs 2 x XLR/BNC with HD Valve Digital Input technology
2 x RCA/Toslink SPDIF Interface
1 x 24/192 Asynchronous USB Input
Analogue Inputs 2 x RCA per channel
Analogue Outputs 1 x RCA/XLR per channel
Thermionic Electron Valves amplification stage 2 x 6H1n-EV / 1 x 6H11P fitted
Output voltage (Digital Full Scale) >2V
Frequency Response 20Hz to 20 kHz +0.0, -0.5dB
Signal-to-noise ratio “A” Weighted >100 dB
Total Harmonic Dist. + Noise (THD+N) <0.3%
Dynamic range >90 dB
Channel separation >90 dB
Power Transformer 32 VA Custom EI Transformer (Digital Section)
40 VA Custom EI Transformer (Analogue Section)
Power consumption Standby < 1 W
Power on < 60W
Rated voltage 115/230V~ AC 50Hz – 60Hz
Colour Silver or Black
Dimensions 17.7 in W by 4.7 in H by 14.6 in D
45 cm W by 12 cm H by 37 cm D
57 cm W by 49 cm H by 25 cm D (shipped)
Weight DP-777 25.4 lbs / 11.5 kg
Shipped 34.2 lbs / 15.5 kg

FAQs

FAQ

Q: Why is the DP-777 circuit single-ended as opposed to balanced?

In our opinion, ‘true balanced/balanced’ is sonically inferior to dual-mono (separate left and right channels) in a single-ended configuration. AMR’s background is in Single-Ended Triode amplifiers or SETs as these to our ears, is the pinnacle in audio design.

ALL AMRs including the DP-777 are dual- mono/single-ended. This costs more to manufacture but sounds the most gratifying. We actually wouldn’t compromise on ‘true balanced’ to satisfy the common notion of its being ‘better’.

For example, all Kondo Japan products are ‘Single-Ended’ not ‘balanced’– Mr Kondo (God bless) would rather not build an amplifier than make a ‘balanced’ amplifier.

AMR will not ‘bend’ its sonic principles to assuage the masses.

Q: What is the importance of Bit-Perfect?

Continuing the “Bit-Perfect” tradition as first deployed in the range of AMR CD Processors (through Digital Master I and II), we believe the original signal cannot be better by digital manipulation. Hence, a 24/192kHz signal is best replayed 24/192kHz. Most crucially, the signal should be kept in its original 24/192kHz form; from the Computer Audio Source all the way through to the separate DAC’s analogue output.This oft-overlook point cannot be any less keenly stressed.
This explains why first, the computer software in the Computer Audio Source (OS X or Windows) should not “re-sample” the signal and second, the same within the digital converter.

The DP-777 is the latter stage in the Computer Audio Source. The whole; not only the DP-777 needs to be Bit-Perfect.

In the Technical Papers section, please see:

Technical Paper 6: If the CAS is Bit-Perfect, do all such computers sound the same?

Specifically for Macintosh computers, please see:

MAC OS X: Beyond bit-perfect and Integer Mode by Audirvana

Q: What is the benefit of having 32-Bit and 16-Bit DACs on board?

In keeping with AMR’s core philosophy of “keeping the signal original” to reach the zenith in playback quality, to play CD audio files (16/44.1), the Classic 16-Bit DAC is by far, the most musical and best-sounding DAC. Correspondingly, for playing HD music files, the HD 32-Bit DAC will also be the most optimal. There is simply no way around the fact that the “best of the best” means having the conceived DAC handle the native music file.

Taking this one step further, AMR chose the more taxing path and placed two DACs in the DP-777; for the first time ever, the listener is able to achieve the best of both worlds; by employing the specific digital-to-analogue converter best-suited to each format, without compromise.

In the Technical Papers section, please see:

Technical Paper 2. The HD Gemini Digital Engine; Arduous but the most Rewarding.

Q: What is the DP-777’s “Organic Digital Algorithm?”

The DP-777’s Organic Digital Algorithm is AMR’s unique programming of the HD Digital chipset so that it deals with the sources of “Digital Ringing.” Specifically, these are; Minimum Phase, Apodising and Soft Roll-Off.

The DP-777 also offers alternative digital algorithms; Apodising 808, MP Listen and Traditional digital algorithms.

In the Technical Papers section, please see:

Technical Paper 3. HD Audio: Ringing, why it is undesirable and how to address it.

Q: How does the DP-777 deal with Ringing?

“Ringing” in digital discussions is divided into “Pre-Ringing” and “Post-Ringing” that occur in the recording and DAC chipset. The DP-777’s HD chipset under the Organic Digital Algorithm is the only one of its kind that deals with all three major sources of Ringing; Minimum Phase, Apodising and Soft Roll-Off.

In the Technical Papers section, please see:

Technical Paper 3. HD Audio: Ringing, why it is undesirable and how to address it.

Q: At the DAC, what is Asynchronous and what is AMR’s Asynchronous USB?

“Asynchronous” has become a common term for Asychronous Upsampling. As such, any DAC using such Asynchronous Upsampling or Oversampling (at whatever frequencies) is NOT Bit-Perfect.

The DP-777 is one of only a handful of components that is “True Asynchronous” which means the clocks on the PC are slaved to the stable clock of the DAC.

The DP-777’s Asynchronous USB 24/192 uses USB Audio Class 2.0 in Asynchronous Mode and is fully compatible with USB 2.0 and USB 3.0.

Q: Is the DP-777’s Intelligent Memory System the same as a Memory Buffer as used in other DACs?

Due to cost and complexity reasons, only a handful of commercial DACs use a memory buffer. For the select few that have such a memory buffer, most if not all, use Asynchronous Upsampling, or Upsampling of some form (they must, unless they employ a system equivalent to AMR’s GMT Clock). The memory buffer does reduce the measurability of incoming jitter, however the signal is now no longer Bit-Perfect as a result of the Upsampling process. Further, the jitter may only be partially removed, while another part is permanently embedded in the signal, something that is not readily apparent by simply measuring the clock jitter of the DAC’s clock.

The only way to ensure a Bit-Perfect output when using a memory buffer (to eliminate this source of jitter) is to have a very accurate clock that can intelligently track the input clock (DP-777’s GMT system). This very precise clock works with the GMT/IMS in unison to dynamically track and simultaneously adjust the various parameters of the memory buffer (DP-777’s IMS system). This approach finally eliminates the input jitter AND still keeps the signal Bit-Perfect.

In the Technical Papers section, please see:

Technical Paper 1. Jitter: a Digital Problem that requires AMR’s Digital Solution.

Q: Why does digital Upsampling or converting using DSP not bring additional fidelity to the outputs of a CD or standard definition audio file? Should “re-sampling” not improve the sound?

Referring to “Information Theory” by Claude E. Shannon, it is simply NOT possible to create more information simply through digital processing in a closed system (i.e. no additional new information is injected into the system).
As a result, using a mathematical program to recalculate the music signal means just one thing; “the wrong note at the wrong time”. In other words, the original music signal is now degraded because the Upsampling process is by nature, lossy and not Bit-Perfect.

This is why we prefer to not artificially “re-sample” the music file to preserve the “right note at the right time”. The human ear is highly sensitive to music that has been artificially manipulated; no longer correct, this is one of the core reasons why listeners describe “re-sampled” music as unpleasant using adjectives such as “hard”, “etched” or “detailed”.

Given this stance, AMR’s DP-777 allows the playback of standard definition files using no digital signal processing and filtering at all and by using the “AMR” Button, reading the embedded sampling data, the DP-777 will auto- configure for ‘original playback’.

However, we also offer other options, including Up and Oversampling and different digital filters that can be selected from the remote, simply because these features are expected in a modern product and because the customer should be able to make informed choices. Making such “artificial manipulation” of the signal available but defeat-able rather brings the point home.

Connectivity: Computer > DP-777

Q: What is Asynchronous USB?

The DP-777 is one of only a handful of components that offers “True Asynchronous USB” which means the clocks are on the DAC side and the computer’s USB is atypically, synchronised to the DP-777.

The DP-777’s Asynchronous USB 24/192 uses USB Audio Class 2.0 in Asynchronous Mode and is fully compatible with USB 2.0 and USB 3.0.

Q: Is Firewire Asynchronous?

Theoretically, Firewire may be constructed to be asynchronous. In practice, at present, no commercial asynchronous solutions exist most likely due to issues of complexity such as specific driver needed, problematic hot-plugging , chipset compatibility issues but to name a few. Firewire remains used mainly in pro-audio/video world.

Q: Is the USB method of music transfer inferior to SPDIF?

No, it can be much better than the common garden SPDIF even without Asynchronous Mode. In fact, for the SPDIF to perform on a par with the Asynchronous USB Mode, it requires solutions like Global Master timing (GMT) and Intelligent Memory System (IMS) to ensure the SPDIF connection is every bit as good.

In the Technical Papers section, please see:

Technical Paper 4. SPDIF: an Analogue issue that requires an Analogue solution.

Q: What is USB Audio Class 2.0?

USB Audio Class 2.0 is NOT the same as USB 2.0.

USB Audio Class 2.0 is built into Mac OS X (10.6.3 and above) and many versions of Linux and is supported by Microsoft on Windows. It is set to be promulgated an industry-wide standard to achieve native “plug & play” support in all future operating systems.

The DP-777 requires a minimum of USB 2.0 AND USB Audio Class 2.0 compliant Operating Systems (Mac OS X, select distributions of Linux) or a USB Audio Class 2.0 Driver (supplied for Windows) in order to have sufficient bandwidth for 24-Bit 176.4/192kHz audio.

In principle, higher sample rates and word length could be streamed by our USB solution in the DP-777, however USB Audio 2.0 has set the industry standard at 24-Bit/192kHz.

The DP-777’s Asynchronous USB 24-Bit/192kHz means native and future-proofed playback on OS X and Windows.

Q: How does USB Audio Class 2.0 differ from USB 2.0?

These are two completely different and distinct standards. It should be keenly stressed that USB Audio Class 2.0 should not be confused with USB 2.0. The former as its title suggests, is audio-based and is required to support sample rates above 96kHz (i.e. high-definition music). AMR is one of a handful of companies to have brought such a standard to market following the industry definition of the USB Audio Class standard. The latter (and coming USB 3.0) relate primarily to the data transmission speed and is therefore more generic in nature.

Most USB DACs do not follow the global USB Audio Class standard and hence will require drivers to run on PCs (including Macs, Linux) which may be unavailable/incompatible in the future and must be supplied/updated by the manufacturer into perpetuity; for each new operating system.

Q: Is the DP-777 compatible with USB 2.0 and USB 3.0?

Yes, the DP-777 is fully compliant with the current USB 2.0 and USB 3.0. More information is to be found here: http://en.wikipedia.org/wiki/USB_2.0#USB_2.0

The Music File

Q: Do all computer audio files sound the same, assuming the sampling rate and data length of the audio files are identical?

First there are two different kind of audio files, lossy or lossless. Lossy audio format includes all MP3s and AAC. Lossless audio formats include WAV, FLAC, APE, Apple Lossless but to name a few.

The lossy audio format is by design, not high-fidelity and hence is not suitable for high-end audio playback.

In theory, all lossless audio formats should sound the same. Different lossless decoders utilise the CPU differently. Consequently, among other things, different levels of software-induced jitter is created. As a result, each and every different kind of computer file can sound different to one another.

In the Technical Papers section, please see:

Technical Paper 5. The CAS; why do computers perform SRC and Data Length Conversion by Default?

and

Technical Paper 6. If the CAS is Bit-Perfect, do all such computers sound the same?

Q: What is AMR’s definition of High-Definition (HD) audio?

AMR’s very rigorous definition of HD recordings are those that were originally made at 88.2kHz or 96 kHz sample rates (or higher) and 24-Bit word lengths. The only possible exception is allowing 44.1/48Khz 20/24-Bit recordings as HD (e.g. we allow HDCD as one option).

In no uncertain terms, this relates to the original, native format. Therefore, taking a 16-Bit 44.1/48KHz file and Upsampling it does not generate a “High Definition” source file; it merely degrades the original signal.

The Computer Hardware

Q: Typically, why is computer audio unsatisfactory, even when an external DAC is used?

There are several reasons:

  1. Most computers, be it Windows or MAC by default do not play back music file in a “Bit-Perfect” manner; the music file has been artificially manipulated for the worse.
  2. Most if not all Upsampling software employed in a computer is no match for hardware DSP chips (the DSP hardware in the DP-777 and all its digital sources in fact, offers AMR’s recommended Bit-Perfect selection to negate this issue altogether)
  3. The Computer produces Software-Induced Jitter which is directly proportional to its CPU loading.
  4. The computer’s SPDIF output usually contains a large amount of jitter.
  5. The computer’s USB output also contains a large amount of jitter.
  6. All computers use a switched-mode power supply which generates and injects a vast amount of Radio Frequency and Audio Frequency noise. This noise is then coupled into the HiFi system via ground loops and the mains power supply.

From the above, it is easy to see why most people find computer audio sound highly unsatisfactory.

In the Technical Papers section, please see:

Technical Paper 5. The CAS; why do computers perform SRC and Data Length Conversion by Default?

and

Technical Paper 6.  If the CAS is Bit-Perfect, do all such computers sound the same?

And of particular interest to Macintosh users is:

MAC OS X: Beyond bit-perfect and Integer Mode by Audirvana.

Q: Do all Computer Audio Sources sound the same?

An emphatic NO. While computer audio is easy to setup, configuring it for the highest quality of playback is somewhat more complex and goes well beyond the remit of this FAQ section.

The principle for attaining good sound is attention to Bit-Perfect playback (probably the most pivotal), shutting down/removing non-essential functions; unloading the CPU. These are typical considerations on the software side.

On the hardware side, one must focus upon clean-up of the power supplies, issues of RFI, pollution of the local mains power supply with noise, ground/earth-loops and so on.

The Computer Audio Source is just like any other high-end audio device, numerous stages effect the overall sound quality.

In the Technical Papers section, please see:

Technical Paper 1. Jitter: a Digital Problem that requires AMR’s Digital Solution.

The Computer Audio Software

Q: Which is the best Computer System/Playback Software?

The pace and development of computer audio programs and operating systems is nothing short of breathtaking. No amount of testing, not even by AMR can be called fully exhaustive.

Nevertheless, we have tested the lion’s share and achieved excellent results with both Macintosh and Windows-based computers.

On the Macintosh platform, we recommend Audirvana, a powerful computer audio software program that has been tested along with the DP-777 to ensure an end-to-end, dedicated Bit-Perfect CAS solution.

On the Windows platform, we suggest J. River’s Media Center which is also, a user-friendly computer audio software program that has been tested with the DP-777 to ensure an end-to-end, Bit-Perfect computer audio solution.

The list of such computer audio software capable of Bit-Perfect playback is growing almost on a daily basis. Please feel to experiment.

In the Technical Papers section, please see:

Technical Paper 5. The CAS; why do computers perform SRC and Data Length Conversion by Default?

and

Technical Paper 6. If the CAS is Bit-Perfect, do all such computers sound the same?

Of particular interest to Macintosh users in the Technical Papers section is:

MAC OS X: Beyond bit-perfect and Integer Mode by Audirvana.

Q: On Macintosh OS X, what is Integer Mode processing?

Integer Mode is a feature of the software driver Apple built into the operating system. However it is not part of the documented audio specification for OS X nor USB Audio Class 2.0.

Within OS X, there is a similar process to K-Mixer in Windows (mixing the streams and converting between float and integer) called “Core Audio”. In a sense, Integer Mode’s function is to bypass the Core Audio’s internal mixer and float to integer conversion stage.

By bypassing the mixer and internal float to integer conversion, the load on the CPU is reduced and hence software induced jitter is also reduced. As a result, sound quality will be improved.

Of particular interest to Macintosh users in the Technical Papers section is:

MAC OS X: Beyond bit-perfect and Integer Mode by Audirvana.

Q: Is the DP-777 compatible with Integer Mode?

Yes. As this all occurs in the Mac OS and the relevant playback software, the hardware is not involved because the hardware only ever operated using integer data. The bottom line is that as long as the Audio Device is fully compliant with the specifications outlined by USB Audio Class 2.0, then it will work with all the features available from the USB Audio Driver in OS X.

It should also be noted that Windows ASIO and WASAPI are essentially “native integer mode” for Windows.

Q: What are the available MAC Audio Playback Programs (Freeware)?

  • Audirvana – tested, recommended by AMR (Bit-Perfect playback, Integer Mode Processing)
  • iTunes (if no need to play multiple sample rate material, as sample rate must be adjusted manually for Bit-Perfect playback.)

Q: What are the available MAC Audio Playback Programs (Payware)?

  • iTunes + PureMusic (untested, customer recommendation)
  • iTunes + Amarra (untested, customer recommendation)
  • Decibel (untested, customer recommendation)

Q: What are the available PC Audio Playback Programs (Freeware)?

  • CMP^2 (quite technical, not easy to set up, handles all sample rates transparently, Bit-Perfect)
  • Foobar2K (quite technical, not easy to set up, handles all sample rates transparently, B it-Perfect)
  • iTunes (if no need to play multiple sample rate material, as sample rate must be adjusted manually for Bit-Perfect playback)
  • J-River Music Jukebox 12 (later versions do not support ASIO/Bit-Perfect)

Q: What are the available PC Audio Playback Programs (Payware)?

  • Album Player (music only, excellent interface, supports ASIO/Bit-Perfect, update frequency and support could be better, can use MCE Remote)
  • J-River Media Center – tested, recommended by AMR, (full multimedia, however supports memory playback, ASIO, WASAPI exclusive mode – so excellent Audio, easy to use, built-in ripper and good support for remote controls)
  • MediaMonkey (untested, customer recommendation)
  • XXHighend (untested, customer recommendation)

Reviews

Savvy emotion AMR DP-777 DAC signature edition

Listening to the predecessors, playing the sound is like a scorpion. When you feel that you have already known a little bit, you may be able to touch your feet. For a glimpse of it, only the ‘audio elephant’ is full of appearance. How much fun, this time, I took the initiative to ask the scare pigs to try AMR, a word of mouth, a good voice, “I want to try the microphone, AMR is wrong” Oh! Happy to die, I wrote my heart 3… The CD and DAC first.

(Click name to read original review)
More reviews…
AMR DP-777

Doctor John reviews the AMR DP-777 DAC!

“My friend Tony told me he just bought a second-hand unit of AMR DP-777 for a friend and I could have it for a month. Needless to say, I seized the opportunity as it is a Non-Oversampling (NOS) DAC with a Twist…..I used the coaxial input and only the default BitPerfect II. Sound was exemplary. Ambience Clues This has always been a main concern for me…..Every track in the Channel CD sampler (some recorded in a church and some not) was rendered perfectly…..the DP-777 is very detailed, yet not highlighting artificially…..In many ways the AMR is the DAC for me. With CD’s, it plumbs great depth with complex music, and there is not a weak link. Most desirable.”

Thanks Doctor John!

(Click name to read original review)
AMR DP-777

The AMR is the best DAC I have ever heard personally…

AMR DP-777: In a Nutshell “The AMR is the best DAC I have ever heard personally…”

“The AMR manages to sound very relaxing, enveloping, it captures the listener with its strong musicality, and keeps detailed subdued, never calling attention….The details, presence, sense of space all get wider and much better. In fact, the sound signature changes and one cannot talk about it being so mellow as before, but the sound is still addicting and extremely pleasant….This DAC is the best ‘analogue sounding’ kind of DAC I have had the pleasure of owning, and one could optimize the purchase by using its preamp and saving up on external amplification.”

Thanks Tony of Soundbsessive!

(Click name to read original review)

The DP-777 puts a spell on NewZealand’s Witchdoctor

As Witchdoctor’s Gary Pearce succinctly put it, “As clean as the sound quality was, it didn’t lose sight of the performance. I’d describe it as an un-audiophile sounding pre/server combo that just delivers the sonic goods, allowing the listener to get on with the enjoyment of music.”

We would like to formally thank Mr Pearce. It makes our day when a reviewer has ‘ gorged
myself on a swathe of classical, jazz, blues and pop/rock.’ This is what AMR
units do best, bring the enjoyment in listening to music, in a big way.

(Click name to read original review)

Einsnulls (1s and 0s) – Germany’s Premier digital magazine goes gaga over the DP-777

Christian Rechenbach, the editor had the following to say of the DP-777, “No-one else has approached the topic of CD- and HiRez- music reproduction with so much consequence. The completely unique approaches to perfecting the signals and the resulting sound quality are remarkable.”

Thank you for a glowing review of the DP-777.

(Click name to read original review)

Stereophile reviews the DP-777 Digital Processor

Art Dudley effused… “…from Day One, the AMR produced some of the least fatiguing, most involving, and altogether best-sounding digital playback I’ve had in my home.” Art also gushed…“The AMR was more than a pleasant distraction, more than just an escape from the humdrum,; it provided the very best digital I’ve heard.”

We wish to extend a big ‘Thank You’ from the staff and directors at AMR

(Click name to read original review)
Menu