Have you considered any of the really small but powerful Fosi Audio options? I recently purchased the BT30D to drive some well worn and weathered Sonance in ceilings and I am amazed at the power along with separate tone and sub controls. After years of always wondering I also added the Dayton 10IP66 outdoor sub for some low thump and the whole combo actually sounds great!
There is an even better pro model out now as well.