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?