Its the only one.
Its how I would have built the singlepower (MPX3/Supra/Maestro)XLR amps. The overall design is "kind of sort of" like an SP, and at the same time nothing at all like one. I took the parts of the circuit that I liked (pretty much the output stage and the B+ voltage regulator), and replaced the parts I didnt like (the gain stage, and some little parts of the output stage) with parts that made the whole thing work better.
It still sounds pretty much like a singlepower. I wasnt sure if that was the sound you were after or not.
Im not familiar with any other all 6SN7 amps besides the SP. The EAR/yoshino HP4 is kind of close, and has awesome tone, but uses 6SL7. There were a few hybrids using 6SN7 for gain, and SS for outputs. If you can find one the stacker 2 sounded outstanding when I got to listen to it.
