7.1 Surround on a 5.1 System

Hi there.
I have a Pioneer 5.1 Home Theater system hooked up on my PS3 that can bitstream Dolby TrueHD and DTS-HD MA 5.1.

But I have one or two Blu-Ray discs that have DTS-HD MA 7.1 in the discs, does that affect the surround of my 5.1 system? Or my system can "downscale" to 5.1 automatically?

well on the blu ray disc, you should have the option to play it in 5.1. Not sure if you left in 7.1 if it would just play 5.1, or you'd have missing channels. which in this case would be your middle R and L. Unless there is a bunch of audio recorded on those channels, i'd doubt you'd really even notice.