Upgrading specific components in a tube amplifier

@carlsbad2 Thanks for the detailed information in your posts. What’s your answer to the other question the OP asked:

In your experience, do such modifications lead to noticeable improvements in sound quality?

I don’t see that you’ve relayed what you’ve found noticeable and I think this is a key trigger point for the OP (and others). Given your technical expertise, I’d love to learn about your subjective impressions of, say, how much a capacitor or other change leads to improvements which can be heard.

@apollinaire - just to continue the thought experiment....

resistors - I would think that would depend on what resistors are currently in the Yamamoto and which ones are in the signal path. Considering the price point you are at, the existing resistors are probably not trash.  Thus I would think only minimal improvement or difference.

capacitors - Probably the most likely to change the sound/voicing of the amp.  Again, depends what is in there now and where in the signal path.  Would it be better or worse? or just be different?

tube sockets - I would think it would be minimal change in sound, if any.  Changing them may be more about durability than sound quality, especially if you are swapping tubes a lot.  (At the price range the Yamamoto is in, I would think they are not using 25 cent, bulk purchased by the shipping container, sockets used in the $300 Chinese integrateds on eBay.  (No offence to the builders of said units.  We understand you have price points you have to meet.)

I upgraded my 45, 2A3, 300B, and 845 SE amps cathode RC circuit with transistor/MOSFET shunt regulator circuit. I can now adjust the cathode bias voltage for the power tubes. 

The sound quality improves significant with superb clarity. Real cool.

From pics I can find on line, the Yamamoto VT-52 amp has some impressive parts quality underneath compared to most.  Not saying nothing can be improved, or that you won't like the sound of some different parts better, but it already appears to be fairly evolved, and isn't exactly loaded with low hanging fruit.  

Have tried isolation feet under it?

@hilde45 

"Make improvements of a sufficient degree that I can have moderate confidence there is now better sound."

I agree with the sentiment, for the exactly same reasons. Especially as the "improvements" become more subtle. 

I tend to live life the same way.

Make good life choices and you'll live a longer and happier life.