Even though there are many AVRs and AVPs out there that boast 9 or 11 channels and support the front wide and height channels, most support is at the expense of the rear surround channels. You only need 7 channels out because the rear surrounds become the wides or the highs. It is a trade off and very little source material supports seven channels of anything in a native format. Using the XLR outputs would not accomplish much without some additional switching because it would only duplicate the RCA output so the wides or highs would not get a different spatial signal.