Upgrade capacitors in tube amplifier?

I know this not a tube rolling thread, but I would suggest swapping the 12ax7 and 12au7 tubes first. I recommend trying some 1950's vintage Raytheon black plates. Try to stay around $70 for each tube. For the power tubes you could get some 807 tubes with an adapter.

My advice is, if you’re going to change coupling caps, stick with the various film and foil types, rather than a metallized film. They’re generally more expensive (but not always, depending on mfgs), but are of better construction, especially in regards to lead attachment. In a film & foil cap, the foil protrudes at each end of the rolled cap, and the lead is soldered or welded directly to the foil . Metallized caps have the dielectric protruding at each end, so a conductive paste is applied, which makes contact with the plate. The lead is then attached to this paste (a less reliable form of construction).

 Be aware that, for equivalent voltage ratings, film & foil types are generally larger in overall size.

Another vote for tube rolling first and caps maybe after 750-1000 hours of listening.

All the best.

JD

By the time you install Nichicon caps, V-Caps and some Audio Note resistors you will probably spend half of what the amp costs new.  IMO the Chinese amps are below average in sound and if it were me, I would buy something else - I know that you don't want to hear that sorry. The caps and resistors will open up the sound and probably proved improved bass and dynamics if you want to travel down that path.

Happy Listening.

@chinook9, There are 7 film caps in there. The two on either side of the chassis appear to be the coupling caps. The two towards the front of the chassis appear to be doing additional filtering for the input tubes, they are tied to what appears to be a ground buss bar across the front of the amp.
The 7th cap appears to be on the power supply. The biggest improvement will be on the 4 coupling caps. Next would be the two caps acting as filters for the input tubes. Also agree with bigkidz though. If you add really good caps, they are likely to be 30-60 bucks each, and will quickly approach a significant portion of the amp cost. The amp appears to be made by same factory that makes the RFTLYS amp. good build quality; only a small notch down from the factory that builds the Primaluna and Cayin amps.

Have you tried any different output tubes? give the shuguang Nature sound series black glass a try. they sound quite good.