Hum in speakers

Go to Home Depot and get a "cheater plug". Try to get one that has 2 spades, and no ground (long, round) connection. If they only have the grounded type, just cut off that round pin. Plug your cheater into the wall with the amp attached. If that doesn’t do it, try unplugging the cheater with your amp connected and reinserting it into the wall upside down. Post your results.  May the force be with you.

With the Amps just plugged into the speakers the hum is still there

Is the preamp disconnected or just turned off? If off disconnect the preamp at the amp end. Also is the hum coming out of both speakers? Does the hum occur all the time? Which amps do you have? Some amps are known to have a low level hum.

Do you have a dimmer switch on the same circuit as your system?

Hum comes out of both speakers it is all the time they are Sierra audio Denali mono blocks 

There is a dimmer switch which controls a ceiling fan