hi myles. i bought a musicman 75 head about a month ago and it needs new tubes. it has a pure solid state preamp and 2 6L6's in the power amp. i heard this amp has a plate voltage of 750 volts. I talked to the guy at KCA NOS Tubes and he said he didnt think he had anything that would be reliable in my amp. are there any tubes that will work for my musicman? thanks.