Originally Posted by BlackbeardBen
I'm not sure how I would ground the amps without using the existing electrical infrastructure (i.e. the wired ground), and to tap into that I'm either going to need to hack up an extension cord, make my own, or buy a commercially available product to do the same thing.
It's not like I can go sink a 6 ft long copper pole in the ground outside my balcony and run a wire up to my apartment...
Your basic problem is you have a nice 3-pin grounded plug on your amps, but your switched outlet on your preamp is only 2 pins. So, the Ebtech Hum X won't help you. You want to use the two pin outlet and still ground the amps.
One question, though first: does your preamp have a 3 pin grounded plug too? If not, you may actually be creating more of a problem by grounding your amps. Any ground leakage in the preamp will flow back through the shield of the output cable to the amps, then from their chassis to ground (assuming you find a way to ground them). Might want to just try it without the ground first.
The center screw that holds the cover of any outlet is tied to the conduit, which is grounded. That's what the small metal eyelet on the "cheater" is supposed to be screwed to, and that screw is at the same ground potential as the third pin. If you don't want to hack up an extension, you can just run a wire from a screw on the amp chassis to the center screw on an outlet. However, if you ground your amps this way, you'll probably want to ground the preamp that way too. Could end up with quite a knot of wires on that outlet screw.
Or, like I say, just float them all. Unless there is a problem with leakage to the amp chassis, it'll be fine.