I have a TMB 18 Watter built from a GDS Kit. I run it in a combo with a Celestion Blue 12" and a Weber Silver Pup 10". It is a killer amp. The Marshall-voiced side has one tone knob and a volume. It runs from a 12AX7. I tried a GT/Mullard copy and it was too smooth. No high end. I have a JJ ECC83-S in it and it sounds good, but the high end isn't there until you turn the volume WAY up and get crunch. I would like a 12AX7 that has some sparkle before it gets really driven. A good clean tone... Any suggestions? I would like to have it on the edge of breakup and have some sparkle.