I really dig the FAS amps. The Modern III and Brutalz are outstanding high gain amps, the Hot Rodded Marshall one is probably my favorite of all the higher gained Marshall models and the Buttery is so, so sweet. I REALLY love that Hot Rodded Marshall, it’s pretty much exactly what I go for when sticking a drive in front of an 800, without needing any tweaking.
That said, my main heavy preset is a dual amp one; a IIC++ and a Recto, panned hard L/R and using different cabs. When I go to double track I just reverse the cabs and get each amp on each side, it’s the most efficient way of getting a really full, metal guitar tone. It’s just about stopped me from quad-tracking things because it fills out the sound just as much.