I use a pair of Ampeg B100Rs, with a Radial Big Shot ABY and a Yamaha NE-1 parametric in front of the amps. The Radial has two outputs, plus an isolation transformer (kills hum) and phase reversal. The Yamaha gives me midrange tweakage like a V-series Ampeg, plus acts as a master volume to control both amps as a unit. In addition to the advantages previously mentioned. the dual amp setup allows me to get the sound up closer to my ears without overdoing the volume thing. Also, I can EQ the amps separately and/or send an effect to only one. They look cool, too.
Ampeg Club #347, Thunderbird Club #69, SX Club Member in Good Standing, NJ Bassists #34