230W is quite possibly in the range you are able to get out of the Pioneer give or take a few watts, at least that is what I can get out of my 3808, so I am looking for double that, 500W, for an outboard amp.

You could look for a cheap mono amp to drive the center or even use that one you linked to in bridged mode.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70