I've had a pi for a little while now and used it play around. My goal was always to use it as a controller for a multi room audio setup.
I've recently moved into a new home and there is already some existing wiring for audio.

But I'm not sure how it was designed to be used...
I have several blank switch plates all all over the house in different rooms and they all have access to four cables (14/2 (x2) 16/4 and cat5e).
I've done some reading and I see that some systems use cat5e, and some use the /4 for the controls. But I'm confused because none of these seem to access a terminal end of the cables, just the middle.

Can someone explain how this could've been intended to be used? I know that there is more than one cable set running (I would guess a different set to each room/zone) because the living room has access to a very large bundle of the same cables (4 sets of the above mentioned 4 cable bundles).

And just to clarify, the house is aleady wired for ethernet, so the cat5e in the walls I am mentioning is not for that.

The guy who built the house was planning to setup a multiroom system but said it was really expensive and so he didn't, but I would like to be able to do this with a few pi systems and achieve a multi-room setup.

Any advice/direction would be appreciated.

Thanks,
~B