I know I keep talking about this but is it possible to BRIDGE 2 of a receiver's channels together? In other words, bridge the 2 fronts to the 2 rears instead of bi-amping the front speakers with the front and rear outputs. The equipment is a NAD T-773.
It could be possible with some additional phase changing devices but I dont know if those exists and if it's really worth it. Bi-amp or get an additional power amp if you really need more power.