Room treatment and EQ your subs, then switch to a 2-channel integrated. :) You don’t have to have room correction to EQ subs but they sure help.
Another alternative is the Anthem integrateds or 2 channel preamps with ARC
For room treatment, the GIK Acoustic Soffit Traps are really hard to beat in terms of lower octave performance. 2" panels can't perform well below ~ 100 Hz or so.