Not being a metal player myself, I'm always on the outside looking in. But it seems to me that metal is an extreme genre, where more = more, and over the top is the ideal. So given the extreme volume and power required to do it right, how could a single 2x10, or even a pair of 2x10s even begin to cut it? A good 8x10 or 4x12 with a good, high-powered head - like a Mesa Boogie Titan V12 or a Gallien Krueger 2001RB - would seem to be the minimum necessary to play in the game.
MM
I'd say, as always, it depends on the others in the band. Sure, when you're up against a bongo and acoustic guitar, 8x10 is always overkill, no matter how hard the bongo player hits.
Metal is more prone to being played at high volume levels. The guitar player might want to get saturation from the powertubes and cranks his amp and there are not too many drummers in amateur metal bands that are able to play a fast, aggressive style without hitting hard. Also, IMO the bass in metal can benefit or suffer from the placement in the room. When i walk around during rehearsal in my rockband, there are places in the room where the bass is really loud and boomy and other places where it is completely drowned out by the other instruments. I like an amp that is able to compensate for this without breaking a sweat. The harder the guitar's distortion gets, the more i crave for a clean sound to cut through. 412 and 500W does this for me.
On most gigs i can easily do with 212 and not even turn the master beyond noon. I bring the second cab anyway and leave it in the car if the bass is loud enough.
