The sluggish triggering could be resolved by increasing the sub trim at the receiver and turning down the gain on the sub's amp, as stickpony suggests. Here's another possible option just for troubleshooting purposes: set the sub to be on all the time and see if the pop disappears. If it's related to the auto-on sensing, this would eliminate it. If you still get a pop in that case, it'd be time to call Paradigm back.