I'm a metalhead from way back. Although I wouldn't call myself a metal player (don't have the chops to pull it off.)
I do have a MI Audio Tube Zone, which does great Boogie Recto sounds. Tons (tonnes?) of usable gain.
Back in the 90s, I had a Yamaha T50 head. This was designed by Michael Soldano and built by Dennis Kager who designed Sundown and Pignose amps. The T50 wasn't quite as good sounding as the Soldano SLO, but it sounded pretty good in its own right. Again, lots of usable gain on tap. The clean was kind of sterile, but it did two great gain sounds: with the master down and the gain all the way up it had a very liquid SLO/Recto (but low volume) sound. With the gain on about 1-2 o'clock and the master up it did a great crunch sound. It had a great-sounding slave output.
Like an idiot, I traded it for an ADA MP-2 and two months later ADA went belly up :thwap I never could get any usable sounds out of the ADA.