I think I missed the part where you said how the Unidisc performs as a preamp. Isnt that thing pretty silent? How does it sound, anyway?
Yes, my Unidisk SC which happens to be for sale right now has a variable level output and does not need a separate preamp. Without preamp the sound is clean and airy. VTL preamp added more fleshed out midrange and dynamics, and I liked the sound with VTL more.
Tvad, if you are near California you are welcome to drop by and hear the noise in person. I don't know how else to describe this. It's random background noise, not a hiss, not a hum, but nasty sound that makes your ear fatigue after short listening. Not audible when the overall gain was 10dB lower, but audible to 8ft away now. I don't care about the noise that I can't hear in the listening seat.
I wanted to get a new set of tubes as well, but the vendor on the phone was honest to tell me that new tubes are not likely to reduce the background noise at the cost of sales for him. I might just try a new set of tubes anyways because it doesn't cost too much to try.