My favorite thus far: 6L6GC / 5V4G / 6DJ8.
Specific favorites:
- Output: Groove Tube Gold Series GT6L6GE Performance Rating 5 (#2: Russian military 6P3S-E, #3 Tung-Sol 6L6G, #4: KT150)
- Rectifier: Sylvania JAN 5V4G (#2 : various 5V4G & 5V4GA, #3 Mullard 5AR4)
- Input: Amperex 6DJ8 (Holland)
Here’s the output tubes that I’ve tried:
Zenith 6V6G (vintage)
Sylvania 6L6GA (vintage)
Sylvania 7408 (vintage, 6V6 variant)
Mullard EL34
Bugle Boy EL34 (vintage)
Russian 6P3S-E (Russian military surplus 1980s 6L6GC equivalent)
Groove Tube Gold Series GT6L6GE (6L6GC)
McIntosh branded GE 6L6GC (vintage)
GE 6L6GC (vintage)
Tung-Sol 7581A (6L6GC variant)
Tung-Sol 6L6G (6L6GC in a big bottle)
Gold Lion KT88
Tung-Sol KT150
Rectifiers that I’ve tried: 5Y3, 5U4, 5U4GB, 5V4, 5V4GA, 5AR4 (multiple manufacturers of each).
Front-end (9 pin miniature socket) tubes that I’ve tried: 6CG7, 6N1P-EB, 6DJ8, 6N2P-EV, E88CC.
I probably should have bought “socket savers” – because according to my notes I’ve conducted 90 tests. I think I’m done tube-rolling for a while.
The good news, I’m very pleased with sound quality.
My system where the Inspire amp is installed:
- Inspire Inspire “Fire Bottle” SE Stereo Tube Amplifier HO (originally equipped with KT88)
- CD/SACD player: Oppo DV-980H (provides crossover to subwoofer)
- Speakers: Klipsch RF-7II
- Subwoofer: Klipsch R-115SW
Music: Classical, opera, big band