NAD C510 vs M51

[caustic386]

I'm having a hard time understanding something - I'm shopping around for a new DAC, and the NAD M51 comes highly rated. About a year ago, NAD released the C510 with identical specs. However, it's $500 cheaper than the M51 with the difference being the M51 boasts a better power supply. I asked the sales rep what that means in the real world, and he literally said "I couldn't tell you." So if the 2 units have literally identical data sheets, what does one get with an improved PSU? Specs below, from the service manual for each unit:

M51:

Rated distortion (THD+N with AES 17 flter) <0.0005% (ref. 1 kHz 0 dBFS)
<0.002% (ref. 1 kHz -60 dBFS)
IM distortion <0.0001%
Signal-to-noise ratio < -123 dB (ref. 0 dBFS 2V out)
Channel separation > -115 dB (ref. 0 dBFS Volume -1dB)
Sample rate 32 kHz to 192 kHz (USB and digital S/PDIF)
Frequency response ±0.5 dB (ref. 20 Hz – 96 kHz @ 192 KHz sample rate)
Output level 2V (ref. input 0dBFS)

C510:

<0.0005% (0dBFS) <0.002% (-60dBFS) IMD Distortion 0.0001% Signal/Noise Ratio <-123dB (ref. 0dBFS 2V out) Channel Separation >-115dB (ref. 0dBFS Volume -1dB) Sample Rate 32kHz to 192kHz (USB and digital S/PDIF) Frequency Response ±0.5dB (ref. 20Hz - 96kHz @ 192kHz sample rate) Output Level 2V (ref. input 0dBFS)

 

[jdmccall]

The styling is different, the C510 having the "Classic" NAD look, while the M51 is styled to match the "Masters Series". That and just the fact the M51 is aimed a bit more up-market might explain a lot of the price difference. I doubt if I could hear any difference in the performance, but that's just me.

 

[caustic386]

The styling is different, the C510 having the "Classic" NAD look, while the M51 is styled to match the "Masters Series". That and just the fact the M51 is aimed a bit more up-market might explain a lot of the price difference. I doubt if I could hear any difference in the performance, but that's just me.

That seems to be the consensus - it's mostly a matter of aesthetics. I did actually get my hands on the C510 - my "review" would be that there's almost no way I could pass an A/B test between it and my Oppo 105 whereas the Benchmark DAC2 I'm also demoing is quite noticeable on most recordings. Everyone I talked to about the NAD's (including NAD emplyees and the store where I purchased) say that the C510 and M51 are 99-100% identical sonically, so I think I found my answer. All fine pieces of gear, but with my ears on my setup the DAC2 wins out.