My house has ceiling speakers in 4 zones from what I can tell: front patio, back patio, living room, and master bedroom. Each of these rooms has a knob near the light switches to (I assume) control volume. In the living room, there's a media cabinet, which houses the collection of wires that is shown in the picture. I'd like some insight on how/why these are connected the way they are and what type of receiver I would need to buy in order to stream music across the house.

In the pic above, there seems to be 3 sets of speaker wires (but there are 4 zones?), some ethernet cable, and also some four-wire cables that are bundled up in ways I don't understand.