When my PV-10 (that I had for 17 years)needed repair (a tube arced and blew it out), I sent it to Bill Thalmann at Music Technology. IN addition to the repairs, I had him do his mod package (which included replacing the original caps with "auricaps", among other changes). The pre did sound more accurate and "faster," but it may have lost some of the ambience and warmness that it had originally. Unfortunately, I don't know if it would have improved over time, because after a few months, the same thing happened again (probably my fault, I put in a tube I shouldn't have). Unfortunately, Bill never responded to my E-mails after that. I couldn't afford to have it fixed again, so I sold it as is, and went back to solid state (Emotiva, with a Yaqin CD-1 tube buffer). Personally, I was never happier with my CJ than when I had a Bugle Boy and an RCA triple mica black plate 5751 in the line, and Telefunkens in the phono. The mods made a difference, but I was always happy with the original sound of the PV-10. (great midrange and phono stage). I've always had a SS amp (Adcom, then Classe).