Any of the old Polk Audio speakers that have the multiple 6.5 inch woofers and the passive bass radiator. They are the best bang for the buck and can handle all the power that you can throw at them. Just ask anyone that has ever owned them and they will agree that these speakers can rock.
What is the best HEAVY METAL speaker?
I know totally blasphemy question here on Audiogon. But you like what you like, right? Anyway, I know most metal music is totally compressed and recorded horrible (aka Metallica) however there is a new age of metal bands out there that are starting to change that (Opeth started with Blackwater Park). So what speakers out there can take the pounding of a double bass drum kit hitting at full throttle and give the roar of metal guitar justice. There has to be a set up that would make Glen Tipton turn his head and say hell ya!