Quick question for anyone willing to help. I have a Rivera Clubster 45 that I would like to use with a 112 or 212 closed back ext cab to beef up the bottom end. Is there any way to run the ext cab and still use the internal speaker in the amp also, with only one 1/4" speaker out on the rear panel? Any adapter, cable, etc.... I replaced the 70/80 with a V30 but would love to put the 70/80 in an empty Avatar cab and use them both simultaneously.