My current rig is a Shuttle 9.0 into an 8ohm Schroeder 12PL for two bands - 80s cover and 90s influenced hard rock original. Sounds great for both although I'm looking for more headroom with the hard rock band. My original plan has always been to add a second 8ohm 12PL but looking used right now at a 4ohm Mesa PH212, but I'm pretty open to other cabinet combos that would increase headroom. Would I increase volume significantly with more speakers? The Schroeder is so efficient, I'm not sure how it compares to other brands in a band context. Any suggestions?