Sub cable is analog, pretty much the same signal level you get from CD player to receiver, preamp to power amp etc...

The big deal with sub cables, I guess, is that you can hear hum quite well so getting a decent cable for a longer run is probably worth a few extra $$

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