In my last post I stated the subwoofer I was trying to use was manufactured by SVS. This turned out to not be the case. The manufacturer is Bay Audio and the model is a JAM subwoofer. It is equipped with a 325 watt amp. Anyway, the noise problem remains whether I run it in parallel with the hafler/radio shack sub combination or alone. Has anyone else had any experience with this subwoofer?