Hi John. I'm using the subs high level inputs and outputs on the subs. I run the speaker wire from the amp directly to a subs high level input and then another wire from the subs high level output to the surround. By doing this I'm using the subs high pass filter. My subs have two crossover knobs on the back. One for a high pass filter for when you set them up the way I do and one for low pass so you run a sincle sub cable and let the pre-amp send a LFE signal. If using a single sub cable then the low pass would be used. In my setup the high pass filter is used.
