Wire has inductance along with resistance. This can result in an audible attenuation of high frequencies in longer cable runs with low impendence loads.
Twisting the conductors cancels out inductance much like the twisted pairs in data cable.
If you don't want to spend (waste) your money on the esoteric 4-conductor twist, the ghetto method is to use 16-4 jacketed speaker cable as a two-conductor by connecting conductors together in pairs. This yields the same resistance as 12-2 along with the inductance cancelling twist.
For subs, twist does not matter so anything goes... fat parallel lamp cord, romex, THHN etc.