The Fidek amps that SVS use to sell hae balanced inputs and are bridgable into 1 channel. Dont let the fan noise scare you, it costs about $2 and about 30 minutes to get rid of it. I just fixed mine and if I could do it anyone could. The fan noise is gone now. There must be a few floating around for sale or trade
Any professional amplifier could be bridged to one channel and has balanced inputs. Crest, Crown, QSC, Ashly are all excellent, Mackie, Peavey, Fidek are decent.