As nothing is affordable on the open market, I'm planning on building
a switching box so that I can connect two 5.1 sources to the 5.1
analogue inputs on my amp. I was planning on using 3 double-pole
relays (BT47's) for switching the 6 channels. These would be
switchable by a front panel switch. Obviously, the unit would run
from a 12v power supply. How well would this work? Would the relays
cause sound quality issues? Any help would be appreciated.

Marky P.