How to lower noise floor through mods?

I've investigated replacing the electrolytics in my Cayin power supply with a better electrolytic. Problem is the Black Gates/Rubycons are too low voltage rating (at least I've not found a source for higher voltage) for use in power supplies. I suspect he probably has decent electrolytics in his power supply, likely some better model of Nichicon, bypassing/shunt with film caps may be his best bet. I'm going this route in my power supply.

I believe coupling caps are the biggest bang for the buck, sonically speaking, these should be somewhere near the signal tubes. Not a job for the novice, find an experienced tech.

Have you thought of adding a power conditioner to your system? This made a big difference in my system.

There's some gear that responds extremely well to balanced AC. Had a SFL tube preamp that was a completely different beast when given 60/60.

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...

IMO/IME its a Bad Idea to bypass coupling caps. The result is smearing. The more resolution your system has, the more you hear it. On low resolution systems it may sound like that cap got speeded up a little.

Your best shot is to put in the best coupling cap that you can.

If the power supply does not have the tube visible in plain sight, then its not there. A can over the tube would overheat it!

If you decide that you really want to tinker with this preamp yourself, **do yourself a huge favor**: go out and buy a kit from PAIA.com or bottlehead, build it up and make it work. It should look like it was built by an expert inside. Seriously, this is important because you can get in over your head very quickly modding things! There can be shock and fire hazards, both to yourself and others, plus in the real world probably only about 5% of the total modified units ever wind up being better than stock- in the other 95% the mod is a destructive act.

After you have built the kit, look into how it is built and see if you can mod that to do better. If not, don't attempt it on something that came ready-built! Above all though, this is supposed to fun. Don't loose sight of that either.