You need a LOT more bandwidth to push a digital signal through the wire. Analog signals need (say) 20KHz, 5.1 digital needs at least a few MHz...

I learned this at the tender age of 19, the first time I tried to run a 4 GHz satellite signal through a jumper cable. It was the strangest thing, there was signal at one end but NOTHING at the other end

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8