Been a couple of stressful weeks around here with an ill kitty and super busy with work, so I haven't really sat and listened to the system, but last night and tonight I have for a few hours. Here's what I posted in another forum last night...
Swapped the 6FQ7's with the 6CG7's and vice versa. These two pairs of tubes sounds virtually identical. This also means that both pairs of tubes sound excellent. The only thing I think I might hear different between them is that the 6CG7's might possibly have a slightly quieter/darker background, but that's really splitting hairs.
Listening at levels of around 75 dB to 80 dB all evening long, and one thing I can definitely say about these tubes, they have a very intimate presentation. You get a private performance with a really good "picture" of the venue in which the performance was recorded. A wide, deep, vast landscape of sound. Even at these low volumes, you still get that percussive, tactile impact of dynamics. I'm not referring to bass here either, but rather that of say a snare drum, musical wood blocks and the like.
Treble detail such as triangles, cymbals, top register of a piano or guitar have a natural decay and shimmer to them that gives you that "you are there" feeling. Tambourines and bongos have that fleshy sound. Bass has real texture, tonality and detail.
I have to say, I think that these little tubes alone may just be my new "reference" tubes. I think these are doing the impossible task of out-performing my original go-to reference tube combo of the RCA 6F8G and Raytheon/Baldwin 6SN7GTB... The Raytheon/Baldwin which has been a true "gold standard" of mine for literally 20+ years!
I'm both extremely pleased and extremely shocked at these results to be honest!