Next upgrade?

I have stock 12au7 for the pre and genalex kt77 on the power stage. 
I alternate them with the stock el34, not much difference

@tomic601  thanks for the tip, I ordered the book

I too have an "all digital source" system and I've found that upgrading the AC power conditioner makes the DAC perform better.  I know you said you weren't interested in that upgrade, but it might be the best thing to make that excellent DAC of yours perform better.

@sounasega You sound like you’re in good shape. I really think that speaker, listening position, and room acoustics are the next step. I bought a Umik and downloaded REW software. Using that to analyze the tonality and reverberation in my room -- in conjunction with listening -- changed things dramatically. Dealing with room acoustics is time-consuming and laborious, but are magnitudes more effective at improving the sound. Perhaps those are all factors you can’t change and so an upgrade is your already best path, so I’ll just shut up now!

@sounasega

I have stock 12au7 for the pre and genalex kt77 on the power stage.
I alternate them with the stock el34, not much difference

most primaluna dialogue users find that replacing the two center small signal input tubes improve the sound of the unit

look for a quiet matching pair of old stock rca or ge 12au7’s, sylvania are a touch brighter but still very good, all are much more dimensional and sweet sounding than the rather lean and grim sounding chinese ’primaluna’ labeled au7’s the factory equips the unit with (you can also go with european ones but they are much more expensive and to my ear did not sound significantly better than the old stock usa ones, luckily 12au7’s are still fairly plentiful and reasonably priced unlike good old stock 12ax7's by now...)

brent jesse or andy at vintage tube services will sell you good ones (but andy won’t sell you ge’s he just hates them 😆)

https://www.primaluna-usa.com/tube-rolling

good luck