Pioneer receivers (at least the ones with Advanced MCACC) do have corrections for the sub channel. They have a 3-band parametric EQ with variable Q, and phase adjustment to align them with the main channels. All of this is auto configured.
_________________________
Pioneer VSX-1018AH-K, PDP-5020FD, DV-79AVi
Axiom M22s, VP150, QS8s
Sony PS3, surround backs
-Chris