Again, it comes back to what is more “accurate“. If you think digital truncation of bits is more “accurate”, more power to you. I don’t, knowing the inherent trade offs involved in DSP, and having taken grad level courses in DSP. You need to look at signal to noise ratio of digital audio not w.r.t. 0 dB, which is meaningless, but at the signal level in question. If I truncate the output of Dave to -40dB, the idea that it maintains the same S/N ratio that it does at -3dB or 0dB is absolute poppycock. You haven’t understood how digital audio works then. I suggest reading Alan Oppenheim’s books on DSP or similar grad level textbooks. There’s no free lunch in digital audio. If you believe that, their marketing propaganda has worked. Pay close attention to how distortion rises sharply in digital audio as signal level drops.
The idea that a balanced tube preamplifier with distortion levels around 0.001% is obviously coloring the sound is a bit far fetched. Take a look at the distortion measurements of any recent ARC Reference tube preamp in Stereophile. Or look at McIntosh’s latest model 1100 two chassis tube preamplifier. Their previous generation 1000 preamp came in both solid state and tube versions. For the 1100, they decided to only release the tube version, because, and I’m quoting here, “it is the quietest preamplifier McIntosh has ever designed”. Check out its specs on their web page.
if you think running Dave in preamp mode is the most accurate, I strongly disagree and challenge you to produce measurements that back up your claim (i.e., show me the Dave at -40dB maintains the same S/N ratio it does at 0dB). If you say I like the sound of Dave as a preamp, I can’t argue with you. That’s your personal choice and we are all entitled our choice. Just don’t claim it’s because it’s more accurate. That I’d like to see a proof for.
Regarding the use of external power supplies for Dave, that’s again your choice whether you want to plonk down 10 grand for an external power supply for a DAC that’s already hugely overpriced (The Topping DAC decodes more formats than the Dave, measures better, and costs 1/10th the price, just in case you think the Dave is priced reasonably). But it’s your decision and your money. Once again, I have seen no measurements of any kind that support using the external power supply for the Dave. Does it improve the S/N ratio? Can you measure the improvement? It’s a risky business in any case. If it blows up the Dave, you’re out of not only the money spent on the Dave, but the power supply as well. At least in the case of Naim, they design their products for external power supplies and support it in case something bad happens. Here you are completely screwed if there’s a power glitch and the Dave fries (don’t forget DSP chips are notoriously fickle about static and they are very sensitive to even slight glitches in a power supply).