Hopper Ke;
I have the Nova as well and have been using it for about a month and I agree with you that I have not really been able to ascertain a difference between the tube and the solid state outputs on the pre-amp. I was hoping that the tube would give a slight warmth particularly in the mids, but I have not felt that it has achieved the degree of warmth I was expecting.
My understanding is that there is a mod in the works for a tube swap, but I am unsure of which tube is being considered and if it is in conjunction with any other cap replacement.
I am only using the unit as a preamp, a dac, and on rare occasions as a headphone amp. I am pleased with the dac performance particularly from red-book cds, but not quit as impressed with its performance on the files from the computer or the IPod. Let me know if you find out a good alternative to the existing 6922.
Cheers,
Bruce