I used a bass amp setup way back ( late 70's and early 80's ) when my setup was a Hohner Clavinet and a Yamaha CP25 electric piano. As soon as I added an analog synth ( Korg Poly 6 ) to the lineup, it quickly became apparent that it wasn't procucing the dynamic ranges I needed. I switched to a decent quality PA setup, and the added benefit was that my CP25 also sounded a lot better.
With the avaialbility of good quality kb amps and much more compact self contained powered speakers and PA systems, I wouldn't ever consider playing through a guitar or bass amp these days.
If you're not playing live, you might consider using something like a Logitech powered speaker setup. The Z2300 I have is rated to put out 400 watts or so. I don't know how accurate the specs are, but I can tell you that for my studio it's all I need even when adding other musicians here. My traditional PA system rarely gets turmned on any more in here. The Z-2300 can be had for about 110 Usd or so, and there are smaller systems that would still provide plenty of punch. There are guys at the arranger forum who are gigging with the 5.1 version as their soundsystems( Z-5300 ) and are reporting excellent results.
AJ
_________________________
AJ