It doesn't practically matter for the 500 but the higher voltage will give you more flexibility. Audio gear exists that provides higher output with a higher supply voltage.

Regarding gauge, it depends on length of run, ampacity, allowable voltage drop and conductor material. For a 40 foot run, 10A load and 1V drop, 10 gauge copper is fine.

Last edited by Mojo; 08/08/20 05:55 PM.
House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated