10 gauge speaker wire for 2 12" subs.

[panhandler62]

I don't see how the wire would be a load issue though, how the box is wired internaly could have a huge impact on load. Higher impedance means less load. Load is the total current that actually flows in the circuit.

Overheating and clipping is caused by excess load which is frequently the result of running low impedance speakers in parallel on amps that don't have the capacity to handle that much current.