Well, I finally ended up taking the bull by the horns, as froggies say...
Welcome to Jumper City, population: too much
Ended up way bigger than I wanted to, I guess most veterans here are able to shrink it to half of mine, hehe!
Anyway, I got lucky. After going through it three times to triple-check it (god, I hate opamps when doing a layout!) I built it and it works.
Test gear and notes:
- Charvel 4 w/mid boost, bridge humbucker -> Rocket .45 (thanks again HamishR!) -> DEVICE -> TPA3118 60W class D amp -> 2x12 open back with Celestion V30s
- eq becomes more noticeable as vol. increased
- working better with 60W amp than plugged in DAW with Amplitubes cabsim after it
- seems to be unity vol, with slight increase when both pots are dimed
- 9V is ok, 16V give it a bit more clearness -> do not go up to 18V just in case (opamps)
- tested with TL072 and TL074, check also TL062 and TL064
- almost no noise when tested unboxed, slight 50 to 70Hz hum but fairly unnoticeable
- maybe a good idea to check how to increase resonance, though testing it with 4x12 may prove increase unnecessary
- test it with Speaker Saturation Simulator between preamp and device
- test it full volume in reh.room
Overall, I find it to be a really nice addition for upgrading SS amps. Must run immediately before the poweramp, though.
Those concerned with size will easily shave off some rows and columns by adapting it to conventional wiring (as usual, laid out for 5mm pitch terminal blocks).