I was bored so I thought I would follow up on that post about the Sunn from eBay ('72 Solarus, matching 4x10 cab). Eventually did get it up and running, a lot of drunken times with dad and a soldering iron (oddly enough, we didn't get any scars). Had to build a new feedback loop inside (went by a Fender schematic), put resistors on the tube sockets as they were up to 600V, which is the max KT88s can withstand. Current tube compliment: 2 JJ/Tesla KT88s in the power section, a JJ ECC803S in the preamp, a NOS GE-6AN8A for the phase inverter, and an EHX 12AU7 driving the reverb. Don't use EHX KT88s, they're puny cheap garbage that shoot lightning bolts out under pressure. Tremolo doesn't work, but I have a Rotovibe so I don't really care.
The transformers are fucking huge. Its rated at 60W, sounds like 40 but feels like 100. Most of the power is going to the low end, and the speakers in the corresponding cab are pretty muddy themselves, thinking about replacing the top 2 with Jensens to brighten it up a bit. Its super clean, doesn't break up until about 9, but its not a very usable crunch, I just run it clean and use a fuzz box, plenty of headroom. Practicing in a small garage, I noticed it was hard to make out the frequencies coming from my distortion pedal against the cymbals, and clean I was competing with the bass due to how boomy this damn thing is. I took it to a local coffeeshop-type venue that usually houses full sized indie, jazz and punk bands, was able to crank it there and it rang through clear. Drove the jazz crew out who said we were too loud, but my friends said it could have been louder, no pain in their ears.
Its a decent sounding amp, a higher powered version might be good if you're a guitarist working without a bassist. These are going up in value because of the doom metal crowd discovering them, but the 60W ones aren't even loud enough for that purpose; my other 40-60W amps sound louder than this considerably, but they don't shake the floor as much. Oh well. Maybe I'll get a Super Reverb and run them in stereo, they'd cancel out each other's problems.