Sir ..
you have three subs ??? would two be up front complimenting the front three and one be in the rear of the room ?

kind of the same situation I am after, except I am breaking it down a bit more .

Maybe I will go with four subs. Two up front and two in each rear where the left surround rear and left back rear would share a EP175.
Well, ok I cannot as Axiom subs don't have the filter anymore.

Pioneer sc-1525
M80 HG Cherry