I'm looking at ways to get a cleaner, higher-headroom sound out of a tweed Blues Jr.. Have replaced V1 with a 5751, speaker with Cannabis Rex (was Jensen C12N) and amp has BillM tone stack mod (just the one involving a jumper on the mid pot to get full off on the mids...no tone caps replaced as yet). Also have a replacement output tranny that is waiting in the wings as next mod. I had some 12AT7's lying around, so I plugged one into V3 (actually a NOS Sylvania 6201...high-class 12AT7), and to my ears the amp sounded better/cleaner. A day or so later I turned the amp on and got the dreaded loud hum followed by fuse blow as one of the JJ EL84s failed. My question is could the 12AT7 in the driver position have caused the EL84 to fail, or was it just ready to go and this just a coincidence? I know that 12AT7's have less gain than a 12AX7 but are capable of producing 10 times the current. Are they just not a good match for driving push-pull EL84s (or is further modification to the circuit necessary to make them a good match)? Should I stick with a tube that has more similar specs but lower gain (e.g. 12AY7 or 5751). Liked the sound with the 12AT7 but don't want to be constantly replacing power tubes.