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NAD Masters Series M51

Stereo DAC/digital preamp (Silver)

19 Reviews | 5 questions - 15 answers

Item # 745M51

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Our take on the NAD Masters Series M51

Sure, NAD's M51 is an exceptionally musical-sounding digital-to-analog converter, but it's much more than that. It's also a versatile digital preamp with enough inputs to handle all of your digital music sources: disc players, network music players, and even your computer. What puts this DAC in a class by itself is NAD's acclaimed Direct Digital technology, which uses immense processing power to transform digital bits into music that's warm, involving, and lifelike.

A boxful of digital audio innovation

Sure, NAD's M51 is an exceptionally musical-sounding digital-to-analog converter, but it's much more than that. It's also a versatile digital preamp with enough inputs to handle all of your digital music sources: disc players, network music players, and even your computer. What puts this DAC in a class by itself is NAD's acclaimed Direct Digital technology, which uses immense processing power to transform digital bits into music that's warm, involving, and lifelike.

How NAD's Direct Digital technology works

NAD's powerful processing engine has exceptional speed and accuracy compared to typical DACs. To get technical for just a moment, the M51 re-samples the incoming pulse code modulated (PCM) signal and converts it to a pulse width modulated signal (PWM) with a sampling rate of 844kHz. One big benefit of converting PCM to PWM is that it completely eliminates any timing errors, known as "jitter," in the incoming signal. That's reflected in the M51's vanishingly low numbers for noise and distortion.

Sound that expresses the spirit and soul of your music

Specifications matter, but they can't describe the energy, presence, and life that the M51 restores to your music. Thanks to this DAC's extremely high clock speed, sophisticated filters can be used to remove nasty digital artifacts like ringing, while maintaining the nuanced dynamics and tonal purity that will make even familiar recordings sound fresh.

All the right connections — including HDMI


The M51 offers an array of digital inputs, plus high-quality analog outputs including balanced XLR.

The M51 is uniquely equipped to dramatically improve the sound quality of all your stereo digital music sources. It has a coaxial digital input, which is great for connecting a CD or DVD player, or a Sonos® Connect player. And an optical digital input is the ideal hookup for your HDTV, Apple TV®, or game console. In addition to these common inputs there's an uncommon balanced digital XLR input that provides an ultra-low-noise connection when used with a compatible high-end CD transport.

High-res audio

A Type B USB port makes it easy to feed the output from your computer into the M51's superb DAC, bypassing your computer's sound card to yield much higher quality sound with stored or streaming music files, including high-res files with sample rates up to 192kHz. (Free USB driver download required for Windows® PC playback.)

Plus, the M51 is the first unit of its kind that we've seen to offer HDMI connections: two inputs and one output with video pass-through. This gives you access to the high-quality 2-channel soundtracks found on nearly all Blu-rays and DVDs. Many symphony orchestras and some specialty music labels are also releasing high-res audio recordings on Blu-ray or DVD.

Praise for the NAD M51 from Stereophile

"The M51 projected a rich, lovely sound that wasn't too forgiving, which was to its credit. I like to hear a recording's technical warts, if any."

"I prefer DACs that reveal as much as possible about what was captured on the tape or in the digits, and couldn't care less about adding a rose-colored tint to dodgy digital sound. In this regard, the NAD M51 succeeds with a wonderfully detailed and revealing sound best described as honest, with a friendly smile. And it was a pleasure to listen to. "

— From Jon Iverson's review in Stereophile, July 6, 2012
Read the full review

It's a versatile digital preamp, too

The M51 is a fully functional digital preamp with one of the world's best volume controls. NAD's 35-bit architecture makes it possible to have a DSP-based volume control that does not reduce resolution — even with 24-bit high resolution signals. In fact, all switching and volume control is done in the digital domain. The only analog circuit is the Class A buffer at the output of the DAC.

Note: input selection is available from the front panel, but volume can only be adjusted via the remote control.

Product Highlights:

  • 35-bit/844kHz up-sampling digital-to-analog converter operating in differential mode for precise sound
  • asynchronous USB technology for reduced jitter and better sound with computer-based audio
  • front-panel vacuum fluorescent display shows sampling rate to verify source quality
  • preamp function with selectable inputs and remote volume control
  • 35-bit DSP-based volume control maintains full 24-bit resolution sound
  • phase-inversion (polarity) switch to compensate for out-of-phase recordings or phase-inverting amplifiers
  • HDMI connections with video pass through to allow two-channel home theater with a Blu-ray or DVD player source
  • remote control
  • two digital audio inputs: one optical (Toslink) and one RCA coaxial
  • USB (Type B) input for connecting a computer
  • two HDMI inputs for stereo-only audio and 3D-compatible video pass through
  • balanced digital XLR audio (AES/EBU)
  • one pair RCA audio
  • one pair balanced XLR audio
  • one HDMI video
Other info & specs:
  • supported sample rates: 32kHz to 192kHz (USB and digital S/PDIF inputs)
  • dedicated NAD USB Audio 2.0 Windows driver required for playback on a PC (free USB driver download available from NAD's website)
  • Mac OSX 10.6 or later includes NAD USB Audio driver, so no download is required
  • frequency response: 20Hz to 96kHz @ 192kHz sampling rate(±0.5 dB)
  • THD: <0.001%
  • signal-to-noise ratio: less than -123 dB
  • channel separation: greater than 115 dB
  • output level: 2V
  • RS-232 port for automated control systems
  • 12-volt trigger and IR input
  • detachable power cord
  • 17-1/8"W x 3"H x 13-1/16"D
  • weight: 12.8 lbs.
  • warranty: 3 years
  • Our 60-day money-back guarantee
  • If connecting to a TV, please make sure you can select "PCM" output in its audio menu. This DAC is not compatible with multi-channel Dolby® Digital signals.

What's in the Box:

  • Direct digital DAC
  • Two 6' AC power cords (US/EU)
  • Remote control (M50)
  • 2 "AA" batteries
  • Quick Start Guide
  • Warranty Card

I have systems in two different homes and own two of these units. A great dac and digital preamp. The sound is superb and the unit provides a wide array of hookups. It has multiple digital inputs and analog outputs. Particularly pleased with balanced outputs for my main amp and RCA's for my sub.

Mark, Wayzata, MN


NAD Masters Series M51 Reviews

Average Customer Review(s):

(19 Reviews)

Transparent and natural

Chad from Greensburg, KY on 5/29/2018

Crutchfield Customer Review (What's this?)

Excellent DAC that can also double as a preamp if you are only using digital sources. Compared to my previous PS Audio NuWave DSD, the M51 provides the same amount of detail without any of the digital glare or harshness. I'm using this with MartinLogan electrostats and the sound is simply amazing. It's almost analog in its presentation. Highly recommended.




Mark from Wayzata, MN on 1/27/2018

Crutchfield Customer Review (What's this?)

I have systems in two different homes and own two of these units. A great dac and digital preamp. The sound is superb and the unit provides a wide array of hookups. It has multiple digital inputs and analog outputs. Particularly pleased with balanced outputs for my main amp and RCA's for my sub.

Pros: Very flexible inputs and outputs. Great Sound.

Cons: none

NAD Masters Series M51

John from Jacksonville, FL on 1/13/2018

Crutchfield Customer Review (What's this?)

Wonderful. What was gritty, scractchy, and screechy becomes smooth. What was muddled and lacked detail becomes clear and natural. The soundstage expands and the instruments emerge. You could spend twice as much on speakers and still not hear the beauty, but you might think that you did. Now l can imagine the DAC blues.

Pros: Clear, natural, expansive, detailed music.

Cons: None

NAD M51 Masters Series

Anonymous from Atlanta, GA on 12/16/2017

Crutchfield Customer Review (What's this?)

Articulate, transparent to the source, musical in the best sense. This Stereophile A+ rated DAC was a good value. At the close out price, if you're in the market for a DAC, it's a no brainer. No onboard streaming support is the only real current feature missing, but just add a Node 2, run one of its digital outputs to the M51, and you've got near reference digital performance for a song.



The quality of the sound improved

Michael from Melbourne, FL on 12/2/2017

Crutchfield Customer Review (What's this?)

After reading Stereophile and What Hi- Fi reviews on The NAD M51, I became very interested in this DAC when it dropped to 1/2 price. My Vincent Audio Hybrid Tube system with a CD-S1.2 CD player, SA-31MK preamplifier and a pair of SP-991 plus mono block amplifiers produces sound through my KEF R700 speakers that is very good to my ears.. These are all class A devices where the first 100 watts out of the amps is class A. Now, I use the CD player as a transport with a digital coaxial cable to the NAD M51 and analog out to the preamplifier. The music changed, the bass tightened up, the soundstage was more focused with better and clearer dynamic headroom. I heard some words on my Beach Boys Smiley Smile album that I could never make out before in one of the high harmonies. I was not unhappy with the sound previous to adding the NAD M51, but I thought I would try it out. Actually, I was surprised that it made so much difference in the sound of the music. I am a mathematician and I was intrigued by the 844K Hz sampling rate and conversion of Red Book CD PCM (Pulse Code Modulation) to PWM (Pulse Width Modulation) using a 35-bit chip architecture. The music quality has improved and I have no regrets about the purchase. At this price point, I think you would have to pay four or more times as much money for a better sounding DAC so the NAD M51 is outstanding value.

Pros: 1/2 price sale, silver matches other components, it sounds better, it is solidly built and heavy.

Cons: None yet, is is not even broken in.

NAD Masters Series M51

Anonymous from Cary, NC on 11/29/2017

Crutchfield Customer Review (What's this?)

Extraordinarily good. I replaced a PS Audio PWD2 with this DAC with no regrets. I would never have purchased a NAD component except that the PWD2 needed to be sent in to PS Audio for repairs. I bought the NAD thinking if I did not like it I could return it. This DAC is not leaving my audio system. Highly, highly recommended!

Pros: One half price (the regular price would have been a good purchase price).

Cons: None.

The New Center of my System

D from ID on 6/29/2015

Crutchfield Customer Review (What's this?)

I was sold on this DAC when I heard how much better ordinary, red-label CDs sounded. Singers' breaths, for example, come across with startling presence, adding a live element that was never there before. Then I began playing hi-res music--wow! The best fidelity I have ever heard--expanded frequency response on both ends, the blackest backgrounds, explosive dynamics, a truly immersive experience. With the addition of a headless music server controlled by an iPad, I am enjoying better sound and convenience than I have ever known. I now realize that without this DAC I would never have known what my carefully curated system was capable of. I also like the adjustable dimming of the display and the fact that the remote controls the volume--especially helpful since my tube-hybrid pre-amp does not have remote control. I agree that the remote needs a light and that the lettering on the source buttons is too small and dark to read easily. But overall this DAC has contributed significantly to my enjoyment of music. The price isn't cheap, but with the prices of truly high-end audio and the quality of this thing's sound, this DAC is a bargain.

Pros: Immersive sound. Optical, USB, Coax hook-ups give flexibility. Remote control volume adjustment (I would never use a control on the unit anyway).

Cons: Remote needs a light and source buttons that are readable.

Amazing Piece of Gear

Drumstix from Dublin, CA on 8/7/2014

Replaced a Peachtree Grand Pre with this after also comparing with the Benchmark DAC2 HGC. The listening test was spread over 10 days after allowing the Benchmark to 'burn-in' for a week. The Benchmark felt very precise and clinical in sound and presentation. The Peachtree sounded very similar, though brighter. The NAD just seemed much more open and natural sounding, with a better sense of timing. The result on my system was that the soundstage seemed to hang in the air in front of the speakers a lot more with the NAD than with the other two. The NAD also made streamed music from Spotify sound better than the other two. This includes the Peachtree's tube buffer which is meant to smooth out harshness. Horn sections sounded better to me on the NAD, with sense of being there in the room. In general, several positive reviews you can find on the web about the NAD and comparisons to similarly priced units like the DAC2 HGC ring true for me. When it comes to build quality, the Peachtree is absolutely the best. It looks and feels like a premium component, the NAD next and then the Benchmark. Test equipment: Source: Oppo BDP-105, Mac Mini running Pure Music 1.x, SONOS Connect, Apple TV DAC/Preamp (Comparison: Peachtree Grand Pre, Benchmark DAC2 HGC, NAD M51 Classe CA-2100 Stereo Power Amp Paradigm Reference Studio 20 v5 Veldoyne DD+ 10 Media: 16/44.1, 24/48, 24/96, 24/192 files on Mac Mini, Spotify through SONOS, CD via Oppo

Pros: Sound Quality, Timing, Sense of Realism and being there, revealing, organic/natural, HDMI input opens up new possibilities

Cons: Lack of volume buttons on the Device. Boot Up time is very slow compared to all the other devices and therefore, when used with a universal remote like Harmony, it's tough to use automated activities that also switch the input on the NAD as part of the macro. I added a soft button for the right input for each activity, so that I can set it after boot up is complete.

Great digital volume control

Ben from San Francisco on 5/31/2014

Crutchfield Customer Review (What's this?)

As a 20 year fan of Wadia, I was skeptical anyone would meet or exceed their digital volume control. This NAD does, and at a reasonable cost and superior simplicity of use. Great device.

Pros: Simplicity of use.

Cons: Remote too general. No ability to control when it goes to "sleep" - results in requiring the NAD be powered on from remote when you also start up your playing device.


Jared C from Utah on 4/4/2014

Crutchfield Customer Review (What's this?)

The reviews from the various sources are spot on about this unit as far as the sound is concerned. The Benchmark DAC HDR was my first outboard DAC and I really enjoyed it but went to the NAD out of curiosity and because I did like the fact that it can act as a receiver of sorts i.e. wife can handle it better and it accepts HDMI with video pass-through, and because her and I watch more streaming tv on the 2.0 system I have than HT setup i.e. the up-scaling is excellent with ROKU 3 video/audio streaming. I love the fact that I can see the sampling speed on the face because it identified a problem that I haven't noticed--my computer wasn't outputting music properly, however, I had a benchmark HDR which isn't comparable to the M51 i.e. the DAC2 does have sampling indication. The sound is spot on with what professional reviewers have said e.g. warm, fun to listen to, full, etc. I have enjoyed it and was looking for a more relaxing sound than the Benchmark, However, I do think the comparison is apples and oranges. I will be attempting to fuse the benchmark and NAD qualities with silver inter-connects, but if that doesn't succeed I will still keep the NAD. Ultimately, the M51 is a unit that has very easy functionality, excellent sound that is very rich, and is aesthetically pleasing and functionally compatible with my other components.

Pros: Excellent sound, great for up-scaling media, great functionality.

Cons: No "cons", just trade-offs.

Amazing Clarity

Drake from Denver, CO on 2/20/2014

Crutchfield Customer Review (What's this?)

Moved up to this unit from a DacMagic100. The clarity and balance is amazing from top to bottom. Complicated passages feel untangled.

Pros: Amazing clarity

Cons: No front panel volume control if used as a preamp.

Class A+

ss from Washington, DC on 12/17/2013

Crutchfield Customer Review (What's this?)

Spectacular clarity. Clean, explosive dynamics. No need for a pre-amp. These are wired into two big Bryston 7BST mono blocks (balanced) and there is ZERO noise. I can pause a music track, turn the M51 up all the way, put my ear to the speaker and hear-- nothing. This level of silence creates a noise floor where every nuance is discernible. I have owned many high-end audiophile grade products, and I'm surprised this doesn't cost over $10k.

Pros: Clarity. Noise Floor. Dynamics.

Cons: Lack of volume control on the unit.

So far, so good

dmc from boston on 9/18/2013

Crutchfield Customer Review (What's this?)

It's early but this piece sounds terrific and offers excellent connectivity and functionality for my 2.1 system. I wish the remote was a little more user friendly and a volume switch would be nice but you can't have everything.



NAD M51 Review

Lance E from Davidsonville, MD on 5/12/2013

Crutchfield Customer Review (What's this?)

Almost can't believe the difference this unit has brought to all of my digital audio, CD's, internet radio, computer, any digital source all into another realm of sonic bliss. Pandora radio has such a huge sound stage now. Worth every penny at this price. Sounds nearly like vinyl on an expensive turn table.

Pros: Instant improvement to any digital source. A real bargain for the price.

Cons: Can't think of any.

Great value: audiophile quality

Christopher from Madison, WI on 5/7/2013

Crutchfield Customer Review (What's this?)

This DAC replaced the Oppo BDP 105 in my computer based stereo system. The improvement over the high quality 2 channel DAC in the Oppo was immediately apparent. Most generally, it had a liveliness to it that I was missing in the Oppo. Sound was also fuller. Just more engaging with a variety of music from a variety of sources. Noteworthy for me was how much better streaming services like Spotify Premium and MOG sounded. That's special. These lower resolution sources sound worse in some high-end systems. As for high resolution sources, my studio master quality download of Berlioz Symphonie Fantastique by Robin Ticciati and the Scottish Chamber Orchestra was a revelation. Finally I heard what I had been hoping for. The beauty of this level of music playback is really something! My present system uses JRiver Media Center and JPlay software on a Windows 7 pc. Speakers are Dynaudio Focus 110A (active monitors). Have to confess that there is one additional ingredient that makes a big difference: an iFi iUSB Power device that simply slips between the computer and the DAC on a usb cable and cleans up the power coming through the usb connection. A bit geeky, but it works for me.

Pros: One of the best DACs on the market at this price with a proven track record of very satisfied users. Display has great visibility. Remote works great for me, and you don't need to use it often except to adjust volume ( there is also an option to lock the volume and adjust it through another component).

Cons: none really. One can always want different features, but this gets the essentials right.


MiltonB from Boston, MA on 2/1/2013

Crutchfield Customer Review (What's this?)

Great Sounding DAC. All the reviews about the sound are right on. Really great, and works well with Sonos and streamed content, although the best sound came from streaming from my MAC through USB (with the automatically upsampling codec apparently employed by NAD but documented nowhere). I love it and will likely be keeping it, but I do have some nits to pick that I interpret as lack of thoughtful consideration for users,. I presume only audio obsessives buy such things, so documentation is actually interesting to us (me). There is a manual (on a CD), but it says essentially nothing except explain the remote. The remote has not light, and the sources are labelled in tiny letters that are difficult to read, and has a ton of buttons that are only for other NAD components. Give me a small one that is relevant to me. No volume button on the unit, only through crappy remote. And lastly, 5 brightness levels for the display but none to turn the display off.

Pros: Sound is Beautiful! (although I am suspicious that, with all of the upsampling and undocumented magic going on within the unit, how software upsampling via USB, of CD quality output sounds so different from direct, unmolested CD quality digital coax that is only using the DAC. I wouldn't think that pre-upsampling would improve the sound from a DAC that does so much internally, but it clearly does. Which makes me wonder.... HDMI video passthrough is GENIUS! Hello Jools Holland!

Cons: No display off. Remote. Documentation. No Volume control on unti, only from remote. plug and play, no options (I like to play a little, read, and understand ). Only one digital Coax input.

Too Good to Pass Up

Tom from Rochester NY on 12/9/2012

Like many others, I've been transitioning over to streaming music - has been a hard sell for me, though, because of quality vs. convenience factors. (My main system is NAD T787 AVR, Marantz NA7004 NW Player, NAD C565 CD, Oppo 93 BR, PSB Synchrony Speakers, 5.2 setup). I've been running Airplay in 3 rooms + patio for a few years, basically as background music, using Apple Lossless files. I've dabbled a bit ripping some of my 450+ CDs to 16/44.1 FLAC via dbpoweramp, downloaded some 24/96 HDTRACKS, mostly just experimenting. Figured that if I could get streamed music to be almost as good as direct play, I'd take advantage of the convenience. The internal DACs in the T787, C565 and NA7004 are all "pretty good", but I found myself constantly switching/upgrading cables, back & forth between analog & digital from some components, etc. Always trying to eek out a bit more from my systems, I tried out various dealer demo external DACs at home. The clear winner in the "up to $2000" range is this NAD M51, hands down. So I got one. Strongest points: clarity, separation, bass definition, and overall soundstage -- from any connected source, including streaming ALAC via Airplay or FLAC via DLNA, and direct CD. Now I've got the streaming quality I was looking for. I'm still not sure exactly where I'm going next with the streaming bit, e.g., dedicated laptop, NAS, larger downloaded HD library, or just finish the FLAC rips for now -- but with this DAC I know I'll be ready!!

Pros: Sound Quality is amazing. Clarity, separation, soundstage, tight bass. My Synchrony towers seem like they're each about 4 feet wide, a true "wall of sound"! And my PSB 300 subs have NEVER sounded so musical.

Cons: Not really a con, but note that the M51 takes a LONG time to break in fully, took me several weeks of nearly constant play before harsh highs and boomy bass went away. Biggest gripe: I would have liked a couple more Coax & Optical inputs, had to reroute a few components thru the Marantz NW player instead of direct to the DAC. Eventually this will sort itself out, when mostly using streaming, but annoying for those in transition.


Jimmyjames from Raleighwood on 9/12/2012

Crutchfield Customer Review (What's this?)

This is a great sounding dac and for the money it should be. I got this dac to decode 24/192 stereo audio tracks found on some Blu-Ray discs and some DVD-A discs. There are also some 24/192 downloadable music files out there that can be sent to this dac via a computer or player like the Oppo 95. Make no mistake, this is a stereo dac. There really aren't any 5.1 or 7.1 stand alone dacs out there that I am aware of. This is the only HDMI input dac that I am aware of that is not some black box kludge made for hobbyists or "pro" audio. With some BD and DVD/DVD-A discs, the only way you will be able to listen to the high resolution stereo tracks other than via an AV receiver or the in board dac in your player (like the Oppo 95), is to send the signal via HDMI cable to a dac like this. 24/192 source material thru this dac sounds PHENOMENAL. SACD for the most part sounds better than CD. DVD-A at 24/96 generally sounds better than SACD. 24/192 audio sounds better than 24/96 audio and it's not subtle at all, like a sledgehammer is not subtle. The classical music cognoscente have known how good Blu-ray audio only discs sound for some time. With the m51 they sound even better. Pity this thing is not 5.1 or 7.1 channel capable and then you would really have something, a true 5 star product. As it is, it is an incredible sounding dac albeit in stereo. Still comparing it to an old $6000 Mark Levinson dac w/24/96 audio. The same music via this dac 24/192, no comparison.

Pros: HDMI in and out. Incredible sound.

Cons: Stereo only

Fantastic DAC

Jon from USA on 8/29/2012

Crutchfield Customer Review (What's this?)

Outstanding DAC. It manages the holy grail in DACs---incredible detail with musicality and no digital glare/harshness. I auditioned 6 dacs before choosing this one. Base is tight, clean, nuanced and with a power and depth that is amazing. Imaging is excellent and wide. Instruments and voices seem to come alive and make you feel like the musicians are playing in your room. You will be able to make out the words in the music that you might not have been able to understand before. Its not cheap, but if you can afford it, then its a real no-brainer, slam dunk. NOTE: make sure you send this DAC a low jitter digital input signal, because, like nearly all good DACs, it doesn't add any of its own jitter but it doesn't perfectly reject jitter from incoming sources. Also, make sure you send the output of this DAC to a high quality linear power amplifier that has good synergy with your speakers.

Pros: outstanding bass, excellent imaging, instruments and voices seem to come alive.

Cons: perhaps price-- but they don't have competition at this performance level for this price


Hands-on research

Product Research



Direct Digital DAC/Preamp: The NAD M51 Direct Digital DAC introduces many "firsts" for the DAC product category: first to support HDMI, first to support USB Audio Class 2 with support for 192kHz, the first to use digital error correction, and the first 35-bit architecture to be found in a DAC. The M51 is also a fully functional digital preamp with seven digital inputs and one of the world's best volume controls. As a "preamp" it is totally noise and distortion free, because all switching and volume control is done in the digital domain. There are no analog circuits except for the Class A buffer at the output of the DAC. Whether you want to get into computer audio, Home Cinema 2.0, or just want to upgrade your CD player; the M51 Direct Digital DAC will get the best possible performance from your digital formats. All this innovation, performance, and flexibility come with NAD's legendary sound quality and performance.

Direct Digital Technology: NAD's Direct Digital technology is unique in both its extreme precision and in its speed. Direct Digital technology uses a very powerful processing engine that operates at much higher speed and with much greater accuracy than typical Digital-to-Analog converters. Running at 108MHz, the M51 resamples the incoming pulse code modulated (PCM) signal and converts it to a pulse width modulation signal (PWM) with a sampling rate of 844kHz. Operating in a differential mode with double precision, the M51 has state-of-the-art specifications for low noise and distortion free sound. The extreme headroom afforded by the 35-bit architecture allows for a DSP-based volume control that does not reduce resolution. Even with 24-bit high definition signals, the output can be attenuated by 66dB (very quiet) before bit truncation begins.

Precision Processing Engine: The incredible precision of the M51's processing engine gives music a vibrancy and transient accuracy that must be heard to be appreciated. The conversion process from PCM to PWM completely eliminates any jitter present on the incoming signal; again, offering state-of-the-art performance in this most important parameter. Due to the very high clock speed and mathematical precision of our reconstruction filters, the resulting audio signal is totally free of digital artifacts like ringing.

Pure Class A Analog Stage: A Pure Class A analog stage with very low output impedance provides the perfect interface to your favorite amplifier. Also, both balanced (XLR) and unbalanced (RCA) outputs are available.


Power On/Off Switch: The NAD M51 direct digital DAC's main power switch is located on the rear-panel. Once this main power switch is set to "On", you can switch the NAD M51 from "On" to "Standby" using the front-panel On/Off button.

Input Selection: There is an Input Selection button on the M51's front-panel which allows you to switch between connected sources (AES/EBU, Coaxial, Optical, USB, HDMI, & HDMI2).

Remote Control: The supplied IR remote provides wireless operation of the M51 and features controls for NAD's matching M50 Digital Music Player (745M50, sold separately).


USB (Type-B) Port: The NAD M51 direct digital DAC is ready for the world of computer audio with its rear-panel asynchronous USB (type-B) input that can directly stream 24-bit/192kHz content from your Windows PC, Mac computer, or  other network-attached storage device (NAS). Your computer will need to meet the following system requirements.

  • Windows PC Users: Microsoft Windows XP Service Pack 2 or higher, Microsoft Windows 7.
  • Mac Users: Minimum Mac OS X Snow Leopard (version 10.6) and later versions.
Note: Download the "NAD USB 2.0 Audio Driver" and install this driver to your Windows computer. Mac OS X Snow Leopard (version 10.6) and later versions already include USB Audio 2.0 drivers (no need to download NAD USB 2.0 Audio Driver).

Digital Audio Inputs: The NAD M51 Direct Digital DAC includes three digital audio inputs; optical (Toslink), one coaxial (RCA), and one AES/EBU (balanced XLR).

  • Digital AES/EBU (XLR) Input: The NAD M51 is fitted with a Digital AES/EBU (XLR) jack to connect high-end audio sources, such as SACD and DVD-Audio players. For high-end sources with higher sampling rates like 176kHz and 192kHz, it is highly recommended that such sources be interfaced with the AES/EBU (XLR) In connector.
  • Digital Coaxial/Optical Inputs: The M51 also features a rear-panel optical (toslink) digital input and coaxial (RCA) digital input to connect your digital audio components. Connect your CD, DVD, and Blu-ray disc players. You can also add NAD's innovative C 446 Digital Media Tuner (745C446, sold separately) to stream and manage your internet radio and NAS devices, as well as local AM/FM broadcasts. The Digital inputs support sampling rates of 32-192khz.
Note: If connecting to a television set's optical output, please make sure that you are able to select PCM as the default optical out audio format from your television's Audio menu. This DAC is not compatible with multi-channel audio signals and will not work with televisions that do not output PCM.

Analog Audio Outputs: The NAD M51 offers balanced (XLR) and unbalanced (RCA) analog audio outputs.

  • Balanced XLR Output: The M51 is fitted with a pair of balanced XLR outputs to connect your high-end or professional audio amplifier.
  • Unbalanced RCA Output: There is one set of unbalanced analog stereo RCA outputs to connect to your stereo amplifier.

HDMI Inputs/Output: The M51 offers two HDMI v1.4 inputs and one HDMI v1.4 output with video pass-through. This opens up the possibility of using the M51 Direct Digital DAC as the heart of a "Video 2.0" system using the mandatory two-channel linear PCM soundtrack from Blu-ray or DVD to make a compelling two-channel high definition theater presentation. Many symphony orchestras and some specialty music labels are also released in HD recordings on Blu-ray or DVD. The M51 is fully 3D video compatible, but there is no surround sound decoding or video processing.

USB (Type-A) Port: The M51's USB (type-A) port is only used to update the unit with future software/firmware upgrades from NAD.

12V Trigger Inputs: With this 3.5mm input triggered by a 12V DC supply, the M51 can be switched On remotely from standby mode by compatible devices; such as amplifiers, preamplifiers, receivers, etc. If the 12V DC supply is cut off, the M51 will return to standby mode.

IR Input: This 3.5mm input is connected to the output of an IR (infrared) repeater (Xantech or similar) or the IR output of another component to allow control of the M51 from a remote location.

RS-232 Port: The RS-232 port allows connection to a compatible PC or external whole-house control system from companies such as AMX or Crestron. NAD is a certified partner of AMX and Crestron and fully supports these external devices.

AC Power Cord: The M5  comes supplied with a detachable 6' AC power cord.

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Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

Quality sound [ Gary  Jan 21, 2018 ]
high end DAC plus has HDMI in (2) and 1 out. Reviews are off the scale for DAC and Pre-amp. Looking forward to hearing just how quiet the Pre-amp is. Will be using both balanced and unbalanced outputs. [ melvin h.  Jan 02, 2018 ]
Looking to complement my NAD Master Series M22 amplifier with a balanced front end. [ L  Dec 27, 2017 ]
Just seemed like a can't refuse purchase price ! [ Jay  Nov 17, 2017 ]
Good Reviews, [ MELMOTH B  Apr 11, 2017 ]

5 questions already asked

I have the M51 and using the Oppo 205 4K player, I was able to pass though a 4K signal using a 4K disc through the M51 to my 4K television. Interesting since the M51 was designed before 4K was in wide use, I believe. [ Joel  Jan 10, 2018 ]
Not that I know of But you can control pro amps with iPad iPhone apps I have crown xti2 amps and this method works very well Set the dac to your liking and control the rest with the software in the amps Hope this helps [ William  Sep 28, 2015 ]
I use the Roomie IR blaster, app, and subscription service which syncs with all my old iPhones. Tip: if you are not good figuring out new stuff find an audio pro or techie to get it programmed for you. Then on every phone you have is a backlit, touchscreen remote. [ Bart  Sep 28, 2015 ]
Not that I know. [ James  Sep 28, 2015 ]
Hey Los I have not used the unbalanced connects so I sorry I can't help My setup is balanced to Crown XTI 2 amps that are daisy chained I can tell you this, the Nad DAC is a quality product and sounds great hooked up through USB if that's your intended use. Zero hum through balanced. Shoot an email to NAD and ask them [ William  May 27, 2015 ]
Both are active at the same time and I've used it in a similar configuration (driving two separate amplifiers) with no ill effects. [ Aaron  May 27, 2015 ]
Yes, they will have simultaneous output. I have the balanced outs connected to my loudspeaker amp and the unbalanced outs connected to my headphone amp - usually only one of those has power at any given time, but I just tested & confirmed there's output to both at the same time. [ Steven  May 27, 2015 ]
Yes. Both the balanced and unbalanced outputs send signal simultaneously. [ david  May 27, 2015 ]
Yes, but of course the gain levels are different. [ JARED  May 27, 2015 ]
The DAC doesn't play any files, by itself. You'll need another source to decode the AIFF file, then decide whether or not to use the NAD as the DAC. [ Kelly  Mar 15, 2016 ]
Hi John, A DAC doesn't actually play audio files - you'll need a media player for that. The DAC just takes a digital signal and converts it to analog for input into your amplifier. If your media player plays AIFF (or any other digital audio file) and outputs digital data over XLR, coax, optical or HDMI, you'll be able to connect it to this DAC to do the conversion to analog. Hope this helps, Steven [ Steven  Mar 15, 2016 ]
Hello Gib, I think it depends what inputs and outputs you use. Otherwise there is a conversion stage. I am going in AES/EBU and XLR out. This is the only DAC I have heard that sounds like a high quality reel to reel. Long break in is true on this unit. [ BRETT W  May 29, 2014 ]
And as Taylor C said, the unit is very quiet. With the volume set high and no sound playing, there is zero hiss or hum. It's hard to get that with a mixer. All of my muisic is stored on a desktop PC. I am not a DJ. This is a home installation. Any DAC will be a plus for you if your going to be using a PC to amp or receiver. Be sure to get a high quality stereo USB cable as short as possible. It does make a difference in sound quality. [ William  May 27, 2014 ]
I not sure I understand your question. The M51 does have balanced XLR stereo outputs if that is what your referring to. I'm using mine with two 6000 watt Crown pro amps. The sound I get now is phenomenal compared to my previous setup where I was using a DI box. Good Luck! [ William  May 27, 2014 ]
Yes. Unit is very quiet. [ T.J.  May 26, 2014 ]