With regards to my 15" DIY cab with an Eminence C2515 speaker, I did some testing: Genz-Benz GBE 400 w/MTD Kingston 5 and Fender Jazz 4 Sounded huge and powerful, but the low B sounded kind of wierd, like it couldn't make up its mind whether to distort or not. Other than that, just as sweet as my Tubeworks. Ampeg SVT-4Pro w/MTD Kingston 5 (not the same one!) Everything on the low B string lost volume. Couldn't find a good tone, but the knob selection was a bit overwhelming. Sounded like a gorilla trying to suppress a fart. A veteran bass player happened by and stated that low note rolloff is a known problem with neodymium drivers. Is this common knowledge? Is this what other players are experiencing?