Lanx, you said the Parasound has the high pass filter? That cuts the bass to your Warfedales. Set the sub woofer to 40 Hz and the Parasound to 40 Hz.
Integrating a subwoofer
I had a 10 inch AR subwoofer I purchase more than 20 years ago. Condition is still quite good at least cosmetically. Everything functions as it should. It has phase switch, crossover frequency and volume adjustments. My amp is a parasound NC 2125 v2 which has a "high pass" filter (HPF) with two cut off frequencies at 20 and 40 hz. My main speakers are Wharfedale Linton with the frequency response from 40 hz to 20 khz. When I integrate the subwoofer (connected through loop out) in without any filtering, the bass from subwoofer is boomy, tempo is off and can not catch up with the bass from the Linton. I experiment the crossover of the subwoofer from the lowest frequency all the way to 60 hz, no notable improvement is made. Then I set the HPF (in amp) at 20 hz, bass is cleaner, more defined but is still not as tight or speedy as I desire. I do not wish to set the HPF at 40 hz because it defeats the purpose of having a subwoofer. Any advise? What should I do to make it the integration better, OR do I need a better subwoofer? Any recommendation?