Yeah, sure, the speakers are connected with traditional speaker cables but with proprietary male connectors on the receiver’s end, so I could either cut off the connectors or get new cables. Rither way, the speakers can be connected to a different AVR.

And I currently have what you describe :

A) PC Audio Card -> 5.1 computer speakers.
B) PC Audio Card -> toslink -> Panasonic BD/HT Combo.
C) Panasonic BD/HT -> HMDI -> Projector.

plus
X) PC Video Card -> DisplayPort -> 4K TV
Y) PC Video Card -> HDMI -> 1080p monitor (in dual desktop mode with the 4K TV)
Z) PC Video Card -> DVI-HDMI cable -> Projector (cloned with the smaller monitor)

And what I’d like would be:
PC Audio Card -> 5.1 Computer Speakers. (to be used with X and Y above)
PC Video Card -> HDMI -> AVR -> Speakers/Projector (to be used instead of B and Z)
Pansonic BD/HT Device -> HDMI OUT -> AVR -> Speakers/Projector

And I pretty much had all that figured out, I just need to know really, if (and how) I can get lossless HD audio from the PC that way.