How to lower noise floor through mods?

I have a power conditioner that i have only ever used for my CD player (which I was using to isolate the other pieces from the CD player (which worked quite well). I can try it out to see what happens if I plug in only the low-wattage stuff (pre, phono, TT). Pretty soon you guys will talk me out of doing anything to it...

Thanks to all so far for responding.

Sns, it indeed is the Jadis I am thinking of working on. I am not nearly as comfortable with DIY as I would like to be.

Atmasphere, thanks for chiming in. The pre is a Jadis JP80, and it sounds wonderful as is, but I can hear where it is a bit off the mark vs other things I have had in my systems so want to try that. Without having schematics, I am a bit worried about going in myself (actually, with schematics, I am a bit worried about going in myself), but in this thread I am trying to learn which approaches will get me what I want. The pre has a separate power supply, which is beefy, and I have never felt it to be lacking. I think it is perhaps the main strength of the pre. I do not know how it is regulated. The newer versions are tube-rectified. At some point in the past, the power supply was SS. According to Arthur Salvatore's website, that started in 1990 and lasted a few years. Mine is a single-digit serial number, which would suggest it was before Jadis went SS, but since the aluminum cylinders in the back of the PS have covered tops, and I have not looked under the deck, I do not know if they are caps or completely enclosed tubes (and I am too much of a circuitry innards neophyte to have any confidence about what I see other than transformers, glowing tubes, resistors, and clearly marked caps (and, of course, I can usually tell what wire is)). Are "filter caps" the output coupling caps? And last question, would you suggest using a small cap in parallel as a shunt cap, as some do?

Atmasphere and Sns, thanks much for the comments, and the warnings. In any case, I had already planned on doing a Bottlehead pre (then changing caps, then adding shunts), to see what it would sound like, before touching the Jadis. Part of it an education issue, part of it a safety issue.