Thank you guys!

I would keep the speakers and the player - the speakers do have proprietary connectors but they connect through standard audio cables - I know this for sure, because I had to extend the length of some of the cables.
And I do still need a BD player as well - for BD3D playback, for stuff that requires a menu, like bonus features and BD Live and stuff and I also need it for when my PC is busy rendering or something and I don’t want to put extra strain on it.

Another problem I have is that I need to still be able to use the normal PC speakers for when I’m not using the projector.