3 prong power cords are used probably to pass some sort of saftey certification or code.
Ground loops are the cause of your own home eletrical ground problems it is not the subs fault.
I stumbled across a Def Tech sub (new) that has the IEC type of connector allowing for a detachable power cord. I found it a bit ironic, but it didn't have the 3rd prong for the dedicated ground.
The more I think about the MFW-15 (yes, I've owned one), I can't believe that they were not able to incorporate class D amplification into the design. The current method was tested by a member of AV123 (Max Cooper) and revealed that it still chews up 15W in stand-by mode.
I'm also a bit surprised that if the 3-prong cord requirement was actually a requirement - but, how did the amp get approved without any external heat sink? There's a smaller, triangular area in the MFW-15 where the amp fits into - but, no real way for the heat to be dissipated. I'm not claiming to be an engineer - but, just pointing out some of the obvious notes.
