Tube Amp, Preamp upgrades -- what did you do that improved your units?

The biggest improvement in my tube system so far has been having a independent dedicated 20 amp circuit installed for my audio and video components. This immediately killed the slight crosstalk/ground noise I was getting in my audio and I listen to TV via cable via sound bar. No interconnect between my audio and video system now. The video/Comcast/interconnects between the preamp was the biggest source of noise. I helped the master electrician run the lines and install the lines as his helper didn't show. I learned a lot and would definitely recommend spending ($250-750 estimate) to have dedicated A/V lines as opposed to expensive Power Conditioner.

@invalid 

i believe the qs line stage is solid state rectified

If you upgraded a point-to-point wired tube amp or preamp, what did you upgrade? 
I assume capacitors, but was there anything else which you upgraded that made a genuine difference for the sound?
I am looking into improving the caps in my Quicksilver stuff, but before doing that, I am curious if there's anything in addition to caps which I should consider.
Thanks.

Gosh hilde45 I must have mentioned this only about a hundred times by now- DIODES! Diodes were the first mod I did to my Aronov integrated back in the 90's. Big improvement in liquidity, layering, just a really nice upgrade and probably still to this day the biggest bang for the $8 they cost me.

Once that worked I went through and replaced all the caps. This was a long time ago, I think they were all Solen, not that great but a lot better than stock.

If doing something like this today I would do not just diodes, caps and (some) resistors, but also put fO.q tape around caps and on circuit boards. Of course before doing anything like this I would first have done all the easy stuff like QSA or SR fuse, Pods, SR ECT, and a good power cord. Then I would think long and hard about replacing electronic parts. All the really good ones are huge compared to what's in there now. It is a balancing act figuring out what to replace, what to spend, what to get and how to get it to fit. It is not just "oh I'll get Deulund". You will see.

@soniccsc1 I just installed 5 independent dedicated 20 amp circuits. So, I'm good there.
@invalid — yes, solid state rectifiers
@millercarbon Thank you for your suggestions! You sound much more comfortable doing the work than me! I'm going to hire someone who's done this a bunch. As for it being "a balancing act figuring out what to replace, what to spend, what to get and how to get it to fit. It is not just "oh I'll get Deulund". You will see."
I agree. If I was going to just resort to, "Oh I'll get Dueland," then this post wouldn't exist, n'est-ce pas?

Before changing the insides, put it on Nordost SortKones or Grand Prix Audio footers.

They made an improvement to every tube preamp I have owned, including a Quicksilver phono preamp