Can you explain what you meant by this: "The 325 can only play the lossy tracks on Bluray, not the lossless tracks. The lossless tracks are a bit more dynamic(especially in the LFE) than the lossy tracks, and that may be why the 325 can hum right through them."
I don't know what "lossless tracks" or "lossy tracks" are. And I do use the LFE.
Lossy soundtracks are soundtracks that are data reduced to get more information on the disc. DTS and Dolby Digital are lossy encoder/decoders, and these sound formats are exclusively used on DVD and streaming. These tracks do not sound like the original masters they are encoded from, and are a little less dynamic than loss-less tracks.

Loss-less soundtracks have no data removed, and is found in the form of DTS HD Master Audio and Dolby TrueHD. To reduce the size of the audio data stream, Dolby is zipped up in a data reduced "wrapper" during encoding, and unzipped at the other end back to the original PCM file. DTS MA is transmitted as a core(for backwards compatibility), with metadata stacked on top which is the remaining loss-less data. These two formats are found on Bluray disc.

Also, what affect if any is there on a 7.2 receiver if you configure your speakers in 5.1? And what happens to the power that is designated for those unused channels?


There is no effect at all. With the additional channels unused, you might have more dynamic power going to the channels that are.