My brother bought a new house today. It has 4 sets of speakers in 4 rooms and in each room also has a place on each wall where there were obviously volume controls (now covered with a blanking plate). The cables for the volume controls are labeled "volume and keypad control". It contains an ethernet cable and 4 speaker wires. It looks like they all run into the living room where there was probably an amp.
Does anyone know if there was a specific system for this? If not, what controls and amp would he need to get it going again?