What do you mean you would use the Nova "as a DAC preamp only"? I assume that means you won't be using the Nova as a power amp to drive speakers.
The Peachtree Nova was designed as an affordable integrated, not as a standalone DAC. Yes, the DAC chip is good, but that is not the sole determinant of sound quality. If you don't need the analogue inputs or the power amp, why pay for them?
If you just want a DAC with volume control and can afford it, I would try to find a PS Audio Perfect Wave DAC either used or at a discounted price new. It is a stellar piece, and the "street" price from some on-line retailers is considerably below the $3K retail price.
The W4S DAC2 was supposedly designed to sound as good as (or better than) the Perfect Wave DAC. One of the reasons the W4S DAC 2 has the HDMI/I2S input is so it can be used with the Perfect Wave Transport). However, Wyred4Sound and their distributors sell the DAC2 at the full asking price of $1,500, so the PW DAC might only cost an extra $750.
Last piece of advice, send your question to Underwood HiFi. Walter carries PS Audio, Peachtree, and Wyred 4 Sound and can definitely offer some guidance (and quote you prices). I have dealt with him before and trust his ears.
