Cost to keep equipment running / on

I know I could probably figure this out with a little math but wondering if anyone has already done the work.  I'm wondering how much it's costing me to leave my equipment running.  Here is the main equipment that I'm leaving on 24 hours / day.

2 SVS SB subbwoofers (not on standby, always on)
Marantz av7500 processor
Anthem PVA7 7 channel amp
2 PS Audio M700 amps

I figure the subs might be pulling alot of juice even when not in use and probably the Anthem PVA7 amp as it's class A/B I believe.

I'm in the Dallas area and I'm paying about 12.5c per kwh I believe.  

Just looking for ballpark numbers as my bill is definitely higher than I feel it should be.