Well said Donnie.

I made a change. In listening to my less than stellar recordings I kept being bothered by a bit of unruliness in the treble that became a bit fatiguing. By process of elimination I discovered this was coming from the Cryotone 12AU7 that I was using in the ZROCK2 and the input position in the SEWE300B. I replaced those with a pinched waist Amperex 7062 in the ZROCK2 and a pinched waist Amperex 6085 in the SEWE300B (both tubes I love) and played around with the gain and. . . well that fixed that.

I still have Cryotone 6922 type in the driver positions in the SEWE300B and those sound great and don't seem to have been contributing to that bit of fatiguing treble.

Edit to add: after posting this and listening a bit I realized that these Cryotone driver tubes had been in place for some time and I added Verafi Audio products to great success since then that have all settled in. . . why not try a pair of my Amperex 7308s in that position and see what those would sound like now?

I did so, put in a pair of white label US made. Sound is great! I love the Amperex sort of house sound, and in comparison to the Cryotone these are less "forward" and there is a small spoonful more room sound, more image bloom, a bit less "hifi" like and more how music played in a room sounds--the polite way to say it may be to say that the Cryotone seem a bit more analytical. I especially like what changes with the contrabass violin and the piano reproductions. (I used to think of this as a dollop of "warmth" but as my power has gotten cleaner and cleaner it seems more as just a difference in tonal presentation, slight, that gives a more "vinyl-like" sound perhaps; in my system now vinyl and cd and SACD almost have identical sound characteristics--a wider gap has closed, a good thing).

I'll leave these in for a spell, and see if the sound continues to seduce me. The Cryotone tubes will sound good in my audio/visual system in the meantime, replacing RCA Holland 7308s there. (Actually the differences between the 7308s and the Cryotones is as easily detectable and appear the same via headphones in the audio/visual system--the Anniversary modded glass resistor fitted CSP3 there really reveal so much--the rest of the system though is a tiny bit less resolving than the main system, and in the larger room the differences via speakers are less pronounced).

Something that has been percolating in my brain after a year, nearly two, of  listening to Cryotone tubes is that the process really does yield good results, and I believe that the claims of longevity are likely true, but . . . the source tubes are still Eastern European or in the instance of a rectifier Chinese, and there are still aspects of these tubes that are fundamental and different than the best NOS tubes. . . the cat's meow would be a Cryotone Amperex 7308 or 7062. . . but that just isn't possible, I understand that.