NAD M51 Direct Digital D/A converter Page 2

What was weird was that, while setting levels, as I switched back and forth between DACs with the pink noise running, there was a slight difference in the character of the sound. After I'd adjusted the NAD's volume trim, the SPL meter read "0dB" for each DAC, but something subtler was going on—the tonal quality of the pink noise shifted just a little in the room. Later, I figured out what this meant musically.

All My Lovely Goners, the latest release from Winterpills, is a great Americana record (CD, Signature Sounds SIG 2044): folky, rocky pop that strikes me as the kind of album I wish Neil Young would get down to business and make—you know, with catchy tunes and harmonies. In this world of accolades for Fleet Foxes and Bon Iver, I wonder why Winterpills isn't getting more notice.

Anyway, listening to the first couple tracks through the NAD revealed the music's wholesome and well-appointed arrangements, which rock out in places but also sport acoustic guitars and harmonies galore. This isn't a demo-grade recording—the sound is somewhat confused and brassy when things get complicated—but via the NAD it was thoroughly enjoyable and never grated. 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.

Next up was Nils Petter Molvær's Baboon Moon (CD, Thirsty Ear 57201). There's a lot going on here, with Molvær's wandering, plaintive trumpet set against a dark, churning background. Here is where the NAD's ability to handle rumbling bass and spatial character revealed a taut and capable DAC. But this album is a torture chamber of tangled bass, and I sensed a very slight thickening compared to the Benchmark. Or perhaps the Benchmark was a touch too thin . . . ?

Exploring this further, I compared the NAD to Ayre Acoustics' QB-9 DAC via both models' asynchronous USB inputs, using my Apple laptop running iTunes and Amarra. I cued up Nick Lowe's brilliant sophomore album, Labour of Lust (CD, Yep Roc YEP-2621), and cranked through the first four songs several times, occasionally tossing in the Benchmark. The NAD had all the inner detail of its venerable rivals, which many lesser DACs lack. All the musical detail was there, and it sounded as if there were more meat on the musical bones than with the Benchmark—though the NAD lacked just a nanotad of the Ayre's punch and square dynamic edges. The Benchmark sounded more like the Ayre in this regard, but overall wasn't as finessed and musically pleasing as the NAD. I would still choose the Ayre if USB were all I needed, but the NAD didn't embarrass itself; in fact, it impressed me, especially in light of its features and lower price.

I also ran my iPad as a digital streaming source, using the clever USB adapter trick that Michael Lavorgna details at No problems running it straight into the M51's USB input and playing a CD rip—Roxy Music's For Your Pleasure (Reprise 26040)—that I'd transferred to the iPad at full resolution. Interestingly, this trick works with the Benchmark too, but not with the Ayre. I tried everything, but could never get the iPad to play through the QB-9's USB jack.

HDMI benefits and limitations
Finally, I connected the HDMI output of my Oppo BDP-83 universal Blu-ray player to the HDMI input on the back of the NAD and popped in a DVD-Audio disc. Because I'd already ripped this disc to the Sooloos as 24/96 files, this seemed a great time to compare the NAD's inputs. I cued up the Doors' L.A. Woman (DVD-A, Elektra 755975011-2) on both the Oppo and the Sooloos and, using the NAD's remote, switched back and forth in real time.

The M51's HDMI input is stereo only; comparing the Sooloos via S/PDIF to the Oppo via HDMI, I heard, right off the bat, a big difference in volume level between the two feeds. After a bit of testing and more pink noise, I found that the Oppo-NAD HDMI combination was a full 8–9dB lower in level, according to the NAD's readout. Once this was sorted out, it was a bit of a pain to go back and forth between the two sources, adjusting the NAD's volume each time, since I couldn't trim each input. But after doing just that several times, it was apparent that Oppo vs Sooloos was as close to a tie as I could hear. The NAD's display reported that the Sooloos was sending the correct 96kHz stream across, and the HDMI from the Oppo was also running at 96kHz.

I played a Neil Young DVD-A in the Oppo via HDMI, and the NAD M51 displayed the correct 176.4kHz sampling rate. I then grabbed an SACD of Mike Oldfield's Tubular Bells and popped it in the Oppo. Uh-oh. This time the M51's display read 88.2kHz—clearly, an SACD stream fed to the M51's HDMI input will be downsampled to PCM. NAD has confirmed that the M51 can't accept DSD audio via HDMI, but can accept SACD playback if converted by the BD/SACD player at up to 24/192 PCM.

Morten Lindberg, from Norway's 2L label, had recently sent a bagful of music-only recordings on Blu-ray that contained two-channel, high-resolution PCM tracks along with surround-sound versions in various configurations. I put the 2L sampler in the Oppo and once again hooked up via HDMI. The NAD's display jumped to 192kHz. Over the next few nights I played several of the 2L discs, even transferred some of the included 24/96 FLAC files to the Sooloos, and bathed in the glorious detail coming out of the speakers. Kal Rubinson and John Marks have been singing the praises of Blu-ray audio for months, but this was the first music-only BD I'd run in my system this way. I now understand what all the fuss is about.

I admit to having been a little suspicious at first of the PCM-to-PWM approach that NAD has taken in the M51. That was before I'd had a chance to live with it for a couple months. Nothing raised an eyebrow, and the claimed benefits in jitter rejection and filter design have obviously paid off.

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.

In other words, bitstream brilliance.

NAD Electronics International
633 Granite Court
Pickering, Ontario L1W 3K1
(800) 263-4641

mrhyfy's picture

Great write up seems like a fantastic dac. 

I love the Marantz AV7005 and believe it offers outstanding performance HOWEVER I think you might be doing the Nad a deservice by feeding a $2k dac into a $1700 home theater preamp.

The particular problem for me is that the signal from the Nad has to run through the ADC first,then the dsp then the DAC in the Av7005.Ultimately you're reviewing the dac in the Marantz AV7005!!

 I realize that you used the pure direct mode but it is not analogue pass through in this receiver. 

Would it be possible to evaluate the Nad dac with the signal DIRECTLY connnected  to your amp?  That's the whole point of having the volume control feature in the dac.

Jon Iverson's picture

Whenever I receive a DAC that can also run as a preamp (with volume, input switching, etc), I always connect the DAC directly to my power amps. I then compare this sound to  running via the Marantz in Pure Direct Mode. Rarely have I (or those who are listening with me) ever been able to detect a difference.  To compare to other DACs (which do not have a preamp function) I usually run everything via the Marantz - maybe not perfect, but as fair as I can make it.

VandyMan's picture



I love that they included HDMI, but who only needs two HDMI inputs? I need five and I don't have that complex a system. Before someone suggests adding an external switch, keep in mind that they sometimes causes problems. I have two devices that refuse to work when run thru a switch (and I tried several brands). Besides, one of the points of a "home theater" pre-amp, two channels or not, is to act as a master control switch to all sources.

Surge's picture


Thank you for the review Jon.  I would be really interested in knowing how it compares to the AMR DP-777 that was reviewed in March.

I know the AMR is $5,000 vs. $2,000 for the NAD; but I am curious to know if in your opinion it is worth the additional cost.

Many thanks

Jon Iverson's picture

Surge - I have not yet heard the AMR in my system.

raykkho's picture

Thank you Jon for the very exciting review.  One thing though is how can someone merge his M51 with an existing MC home theatre setup, when the M51 does not have any analogue input or HT bypass? I hate to add an AB switch before the poweramp but can't see how it could be done any other way. sad

Amir the Great's picture

last Xmass I did a mistake. Paying 15000SDK for the M51.
it sounds vry good as JA's review, if it souns! The USB Windows driver is a hell. Win8.1 find the dac some times!!!
wrot to NAD. answer: M51 was before Win 8.1!!! and?

How... mush time putin on a product? ok, gott back to win7, same hell. the PC find the dac sametimes!

then they came with "NAD USB Audio Driver for Windows 7 and above" wow the king waked up finally!

but problem was the same. M51 sings when Trump write the order!

Even the JA link above is empty. even if the song finish, efter some minuts the dac dyes! turn itself off! and again Windowes can not find it!

I should turn off the dac Not mr. Stidsen! "is there any body at home?"
shall I teche him a warm bird sings better than a frozen one?

NAD does NOT send the first v1.39 firmware to anybody!!! why? Ayatollah's fatwa maybe.

my 15000 NAD does NOT work properly!

a good product is good in evry manner. NAD isn't an eBay $15 dac who NOT works when you want!

ergonomically NAD is NOT wright either. what happen if U can't find the remote? or battery ...
2 small bottoms at front panel (volume up/down) costs $1. it is the Master NAD isn't? after so many years of iconic amps? oh sorry it is a dac not an amp!

the hole gole is playing music when you want. not waiting for the president to push the bottom.

too tired to play on the NAD.


lev80's picture

Yes! its a great product and there is nothing wrong with the M51. No one forced you to buy it if its ergonomically dose not work for you.
I got my M51 early 2014 brand new and never had any issues with it nor its windows drivers, worked like a charm all these years and still i enjoy it everyday. and i don't think i could depart with it although my other PARASOUND gear sound much sweeter but there is something special about the soundstage of the M51.
You should have returned it if u felt that its not for you, as simple as that.