I'm going from memory here, but I think I remember a couple of knowledgeable people identifying exactly what was wrong with the cable installation if you were getting hum, and possibly even the magic words you could use to get the cable guy to go "oh, I guess I could do that... long as I don't have to think..."

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