Concerning the comment about Marantz not using bitstream with Audyssey, that's not a true statement anymore. Here's a quote concerning the Marantz SR 6006 on AVS.

"you will likely never want to use either DIRECT or PURE DIRECT as doing so disables Audyssey. Rather if you want to see DD or DTS, you'll need to set the source device to "bitstream" with Secondary Audio set to OFF...."