Power for two subs.

I have adverse power effects about twice a month, so none of my gear ever gets plugged in directly.  Also, while not as bad as Florida I do live in a lightning prone area. That combination means that I'm never ever plugging in gear directly into the wall.  Your risk aversion may vary.

The rec given by @noromance , is sound (sic). But, make sure your circuit isn't maxed out by the other equipment on the circuit. Subs don't take that much current, but you do want to have a little in reserve.

And, if possible, get a whole house surge protector at the mains. It will make your electronics feel much better.

B

I pigtailed another outlet onto existing outlet to create a single dedicated circuit for my monoblock amps and dual subs, 10AWG wire for all.

If you thought your preamp and poweramp for your speakers didn't need a conditioner, your subwoofer may not need one either.

ADD POWR POWR BAR 8 A/C strip conditioner. 

look in audiogon classified for a smoking good deal.