Also, a complete description of how everything is connected might turn up some possible problems. Describe everything in great detail(its impossible to give too much info). Maybe lay it out in a block diagram, upload that to some photo hosting site and link to it(sometimes screen captures get shrunk and become tough to decipher)
FWIW, I hear no difference between a mix from a PT session and the final bounced file played thru WMP, but, here is how audio is routed:
From Pro Tools: 192 interface>SPDIF out to Presonus Central Station>powered skprs.
From Windows)WMP): optical SPDIF out to Presonus Central Station