rereading Paul’s description of his preferred method of sub hookup using speaker cables and searching on the wev, I am unsure of one way to hook up- can you connect one set of cables from the amps’ binding posts to the sub’s speaker posts which already have the main speakers connected (so you have 2 sets of cables coming off the amp- 1 set to the main speakers, the 2nd set to the sub)? (Rather than going from amp to sub then to main speakers, or amp to speakers to sub?)
I am not entirely certain of the question here, sorry. Some subwoofers can be connected via high level inputs where the output of your power amp feeds the subwoofer’s internal amplifier. These are rare indeed. REL makes such products, but few others do.
In these cases, the main power amp is only feeding a signal and not supplying any real power to the sub.