How to lower noise floor through mods?


I have an older tube preamp which I like very much. It has something of a lush "romantic" aspect which I quite enjoy, and while it is not 'noisy', it is not the quietest pre out there. In addition, I think that one might be able to maintain the 'romance' but improve the transients a bit. I have done a fair bit of research on replacing the caps (which I should do anyway because of age probably), but I am wondering what mods would lower the noise floor.

Will new/better caps help? Resistors too? Tubes? Is it new wiring for the point-to-point parts?

Modders & Manufacturers, please toss your 2cts in! I would love to hear your experiences and wisdom. What will keep the 'romance' and euphony while lowering the noise floor and improving transients?
t_bone
Atmasphere has it right, start modding with something less valuable. You build up your skills on the cheaper stuff, as you become more skilled you become more confident in working on the more valuable pieces. Read some basic electronics books and ask questions at some of the more technically based audio forums.

You shouldn't be scared to start modding, it can pay off in sonics that fullfill your needs. You just have to understand the hazzards of modifying, nothing is fullproof.

I'm not sure I agree with Atmasphere that only 5% of mods are better, up to now I would have to put my success rate at aprox. 75%, YMMV. Doing you're homework prior to diving in is critical. Also, some equipment is not amenable to modding, the manufacturer may have already used premium parts and/or the voicing may already be optimized. I suspect a coupling cap upgrade in your Jadis will give you what you're looking for.
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.
Feet- Isopods , sorbothane, Vibrapods, LAT
Resisters- Vishay
Chassis damping- Soundcoat
Hexfreds
Electrolytics(power supply)- Blackgate, F&T, RDE
Coupling (output) caps-Mundorf gold, silver, ZN
Good tech to get proper direction on caps, optimize wiring scheme,etc.