I have a Hartke HA-3000 amp with a VX series 4x10 cabinet. I can add another cabinet.....but which one? Should I add another 4x10 or the 1x15? I ordered a 1x15 at the local Samash, but they were out of stock and it has already been over a week. They have plenty of 4x10's in stock though. Should I just get another 4x10? Or does the 1x15 really add anything to the sound?