My main system for some time now has been all Atma-Sphere(MP-1, MA-1's) and I'm extremely happy with the sound.
The heart of my second system is the SLI-80 F1, all-triode, direct coupled version. It came with EL34's which to my ears sounded thick, slow, and rolled off at the extremes. I immediately replaced them with Black Treasure KT88's which made a tremendous improvement; think night and day!
I also replaced the Sovtek 6922's(which suck), the 6SN7's, and 5U4 rectifiers with NOS and again huge improvements across the board. Long story short, while the SLI-80 F1 is still somewhat outclassed by the 8 times more expensive Atma-Sphere gear, I can listen to it for hours enjoying every minute. I think it's a fabulous sounding integrated and can't think of anything I'd want to replace it with!
