I have a superdrive 45 in my shop tonight that needs to be running by a saturday gig. It popped a fuse so I believe the power tubes are toast. This is a cathode biased amp so is it possible to replace the KT66's with 6L6's. Plug and play? I have had this amp on my bench for other little things like the Clean volume balance mod that I have done on several Budda's to date . This one keeps coming back with other issues down the line. like bad solder joints on the green(heater line) from the first tube to the second so it burned up the tube. and now kicks the fuse.