[FullRangeMan]

From the AA site:
The NAD M51 is a 35 bit, 844 kHz DAC, preamp and upsampler that supports the newest USB codec for 24-bit 192kHz audio transmission.
Upsampling to 35-bit, 844 kHz delivers a level of presence and realism to digital audio files unlike anything that you have previously experienced. Performance is absolutely breathtaking, as befits a 'Masters Series' component, etc...
Price 1,999 USD
http://www.audioadvisor.com/prodinfo.asp?number=NAM51
Why not 36 bits??

[Dan Driscoll]

The bit depth doesn't mean much, 24 bits is enough to deliver the maximum signal to noise ratio that the human ear is capable of distinguishing. The limiting factors are the sample rate and the rest of the electronic circuitry, not the bit depth.

I am much more interested in the 844KHz sample rate. I am a firm believer that with a bit depth of 24 or higher that the sample rate is the more critical factor. However, I am not necessarily a fan of up sampling; I generally prefer that playback be at the same sample rate as the recording.

As always, IMO, YMMV, etc.

[mhconley]

However, I am not necessarily a fan of up sampling; I generally prefer that playback be at the same sample rate as the recording.

I am the same way... I have yet to hear an upsampled recording that sounded as good as when played at the recorded sample rate.  I have tried upsampling on everything from $600 CD players to $6,000 DACs and there is always something that I cannot quite put my finger on about upsampled playback.  It just sounds somehow artificial to me.

Martin

[Letitroll98]

The bit depth doesn't mean much, 24 bits is enough to deliver the maximum signal to noise ratio that the human ear is capable of distinguishing. The limiting factors are the sample rate and the rest of the electronic circuitry, not the bit depth.

I am much more interested in the 844KHz sample rate. I am a firm believer that with a bit depth of 24 or higher that the sample rate is the more critical factor. However, I am not necessarily a fan of up sampling; I generally prefer that playback be at the same sample rate as the recording.

As always, IMO, YMMV, etc.

I pretty much agree with what you are saying, but there's that one nagging doubt that creeps in, they told us 16 bit depth was far beyond the ability of any human to discern a difference in.  Once again, having heard 24/196 I think what you're saying is prolly correct, I certainly haven't heard any 35 bit machine to compare, but could you expand to us digital dyslexics why 24 bits is enough?  Thanks in advance for any answers. 

[Dan Driscoll]

24 bits equates to a signal to noise ratio of 144 dB, which is just about the limits of human hearing. However, modern commercial electronic circuity typically has a S/N ratio of about 120-125 dB. IOW, the noise floor of the device is higher than the lowest 1-2 bits of the digital word. The noise floor of tube circuitry is even higher. So the bottom 1-2 LSBs don't really add anything or provide any audible information.

OTOH, a higher sample rate creates a closer approximation of the original analog signal. You are capturing a more accurate representation of analog signal amplitude, frequency and phase. Here's a graph comparing the 44.1KHz sampling rate of redbook CD to the 192KHz sample rate of DVD-Audio.

Courtesy of Practical-Home-Theater-Guide.com


You can clearly see that the 192KHz waveform matches the analog signal much more closely than the 44.1KHz signal. All else being equal, the closer match to the original will be more accurate and sound better.

That doesn't just apply in audio, it's true in all digital signal processing. For example, in NMR, where the analog signal levels are thousands of times lower, the analog to digital conversion is typically 16-20 bits, but the sample rates vary from 500KHz to 5MHz, depending on the application.

[Dan Driscoll]

Sorry, double post.

[wilsynet]

Any reviews on this thing yet, from owners or otherwise?  The technology may be amazing and state of the art, but we have no idea how it actually sounds.  New technology in the digital domain is one thing -- implementation and execution with both digital and analog is another. 

Personally, I have not been terribly impressed with NAD, although I confess that I have not heard their Master Series line.

[Dan Driscoll]

NAD has what I consider the signature "British' sound, similar to Naim, Arcam, etc. There's just something distinctive about them and other British manufacturers that makes it relatively easy for me to tell the difference between them and equipment from American and Japanese companies, irrespective of cost or quality. You either like that sound or you don't.

As always, IMO, YMMV, etc.

[SlushPuppy]

There's a short thread over at Computer Audiophile on the M51:

http://www.computeraudiophile.com/content/NAD-M51-Master-Series-DAC-C390DD-Direct-Digital-Amplifier

[randytsuch]

If 24 bits is good, 35 must be better.   

Marketing.

Also, I agree that 35 is a strange number, wonder what drove that?

Randy

[SlushPuppy]

If 24 bits is good, 35 must be better.   

Marketing.

Also, I agree that 35 is a strange number, wonder what drove that?

Randy

Not sure why, but Esoteric is doing it too:

http://esoteric.teac.com/dacs/d-02/

[Sonny]

Not sure why, but Esoteric is doing it too:

http://esoteric.teac.com/dacs/d-02/

To market newer technology and to sell new products that cost more than the older ones...

[Rclark]

 That looks pretty sweet. I'm excited to see the resolution wars escalate. As with the ceiling, up comes the floor.

[SlushPuppy]

To market newer technology and to sell new products that cost more than the older ones...

No kidding.

[Diamond Dog]

NAD has what I consider the signature "British' sound, similar to Naim, Arcam, etc. There's just something distinctive about them and other British manufacturers that makes it relatively easy for me to tell the difference between them and equipment from American and Japanese companies, irrespective of cost or quality. You either like that sound or you don't.

As always, IMO, YMMV, etc.

Not to nitpick but NAD's been Canadian-owned for better than ten years...
( making Canada a world-leader in rubber control knob technology ! )

D.D.

[bprice2]

A positive impression from a new owner at CA.

http://www.computeraudiophile.com/content/NAD-M51-Master-Series-DAC-C390DD-Direct-Digital-Amplifier#comment-127525

I'm becoming more and more interested in this piece of gear.

[*Scotty*]

I think it is a sorry state of affairs that we now have burgeoning numbers war on the DAC front. This is just like THD spec war between the big Japanese receiver manufacturers in the 1970s.
It would be nice if the numbers added up, 844 kHz is not evenly divisible by 44.1 or 96. This means the the stupid thing unnecessarily asynchronously up-samples both 44.1 redbook and Hi-Rez files.
It would be nice if they gave you the option to turn off the up-sampling function. Here is another
problem, (THD+N with AES 17 filter): <0.0005% (0dBFS), now many of us have an AES 17 in our preamp to use with this product? The presence of this caveat pretty much renders this spec meaningless.  See link http://www.audiotech.com.tw/AES17%20Filter.htm
 I remain unimpressed with the numbers contained in the blurb. This thing needs to successfully compete against a DCS stack or the Lenehan PDX DAC in head to listening tests.
Scotty

[wilsynet]

http://www.computeraudiophile.com/content/NAD-M51-Master-Series-DAC-C390DD-Direct-Digital-Amplifier#comment-127525

I'm becoming more and more interested in this piece of gear.

Yes, but the reference he uses as comparison is a Peachtree iNova.  Which is an integrated amp with built-in DAC.  Hardly a fair comparison.  I'm sure the NAD M51 is also better than my Marantz HT receiver too.

[dwk]

It would be nice if the numbers added up, 844 kHz is not evenly divisible by 44.1 or 96. This means the the stupid thing unnecessarily asynchronously up-samples both 44.1 redbook and Hi-Rez files.

Scotty

844kHz refers to the PWM frequency, not an intermediate PCM frequency.

[wilsynet]

I remain unimpressed with the numbers contained in the blurb. This thing needs to successfully compete against a DCS stack or the Lenehan PDX DAC in head to listening tests.

The DCS DAC is $10K?  Granted, the PDX is only $2.5K.