As a follow-up...there is no need to match brands of cabs and head. You can play mix-n-match as much as you wish. As you now understand from this thread, mixing components does require some knowledge of impedence and what both your cabs and head are designed to do. I would advise, however, that if you get a second 4x10, in that purchase you try to match the original brand and model of the other 4x10. The cabs will complement each other.