I agree with the cost being outrageous. I wish some "rich guy" would take one apart and reveal the insides.
Surprising though, the grounding boxes do work well. I use it with my Lumin X1 and with my JL Audio CR-1 crossover. I have a separate DIY box on my Amps and other smaller DIY versions on my speakers. This seems to be the best configuration.
Funny though, grounding the amps and/or subwoofers together with the other equipment degrades the sound quality giving it sort of a congested sound.
I am only talking about signal ground. That is; from the grounding of a rca or spade input/output. Not AC or chassis grounding.
ozzy