Has anyone upgraded their preamp with V-caps?

YES. I have a highly modified (Robert H. Backert mod) Musical Design SP 2B Pre with 6922 output tubes. It's been a work in progress for the past several years. We just added the Teflon/Tin Foil V-Caps in the output stage and the results were nothing short of amazing- to an already world class sound, actually besting anything I have ever heard. I recommend the V-Cap addition very highly.

I'm asking this question myself. Why just the output stage?

Johnmcalpin, I've been told by a respected component designer that, for the preamp, the output stage caps are the most significant definer of the overall resulting sound and that this is where the new V-caps will show off their stuff...while the remaining caps outside of the output stage are usually in the power supply and will not change the overall sound...at least not to most peoples hearing. Of course, some sticklers may argue that point and want to replace them all. If money were no object than I suppose go for "all" the caps but, as I said, just the two output 2.0uf V-caps in my unit will run 600.00.

Done a phono stage with TFTF v-caps. The best my ears have heard ... and then some.

For bigger caps (1.0 uF) I'd opt for th OIMP though.

Regards
Paul