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From what I read, the differentiation seems to be about features and utility, with the M51 being more of a dedicated DAC and the C510 a DAC/"Digital preamp." Connectivity seems to be the same in both cases. Hypothetically, a better power supply might provide more dynamic headroom in the analog output section, but best compared directly in listening. Power supplies are the most expensive part of any component. Hopefully, others here will chime in with direct experience. But NAD is a good choice all around.
Would more headroom assist at lower volumes if properly implemented? Hypothetically of course - I agree firsthand listening is the only way to know. I'm also currently demo'ing a Benchmark DAC2 which is absolutely excellent at lower volumes (important distinction when you have a newborn in the house).
I took a look. These appear to be very similar. The audio output stage and power supply sections appear to be exactly the same, hence the same specs. However, the center section of the board on the M51 is more densely populated and appears to have a smaller DSP or IC in the digital receiver area.
It seems, like stevecham said, it’s a slightly different feature set. IF the C510 operates like a digital preamp, there’s some additional processing on the bitstream data to make this happen.
Interesting idea - I never would've thought to look at the internals, mainly because I have no idea what I'm looking at. Thinking through both poster's points about Digital Pre vs. DAC - they seem to have the same feature set. Same # of inputs, outputs, etc. - no room correction, effects or anything like that. With that in mind, what constitutes one as a pre vs simply a DAC (marketing aside)?
"High end" audio is so confusing...
Reading on these, it appears both M51 and C510 can be used as "digital preamp". Both have a output buffer stage, which should be able to drive an amplifier directly (i.e. no need for a preamp in between, unless you want a specific preamp to help shape the sound). There is no analog or resistor based volume control. The "volume" attenuation is done all in DSP by upsampling the PCM signal and changing the original 16/24-bit word to 35 bits and then reducing the actual waveform mathmatically. This is similar to how Oppo does the digitial volume (bit in 32 bit realm). Everything is done in DSP software and output in PWM DSD type voltage injections. There is no conventional ladder-based DAC chip in use here.
I've never heard one of these, so I cannot comment on sound quality.
I have a M51 and its a great DAC.... I never used it as a pre but it is the best sounding "source" component I've ever owned. It also has the best digital volume I've ever used. In fact the only gripe I have is that it doesn't have some sort of volume control on the front panel, a serious omission if you want to call something a "preamp" . I use a pre without a remote volume so the M51's remote does come in handy. I think they would have sold far more if they had a front panel volume.
It's unlikely I'll ever do away with my preamp so the M51 is perfect for me... If you think it will serve preamp duty for your digital sources the 510 may be better.
Spearit Sound always has demos and factory refubed NAD gear at great prices....you should check them out.
It's unlikely I'll ever do away with my preamp so the M51 is perfect for me... If you think it will serve preamp duty for your digital sources the 510 may be better.It sounds like we'd be in a similar situation - literally my only source is a HTPC, so for all intents it would also serve as my "source." Interesting that you have a pre with no remote volume - I don't think I've ever seen that? (unless you just lost the remote :)