The differences between makers is more about how they offer to manipulate the sound. If you want to pass the audio unchanged, they all do that well.

What I meant by the first part, is that different manufacturers license different "room correction" software, or in the case of Pioneer or Yamaha, write their own. Though with Onkyo and Denon, they've both settled on using the software developed by Audyssey.

Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs
-Chris