(1) check the powered subwoofer manual for input options and also your receiver manual
(2) Assuming you are not considering any direct LFE output from the receiver using a single subwoofer RCA termination cable into the powered subwoofer’s designated LFE RCA input:
- then just connect the receiver preamp RCA outputs to the RCA inputs on your powered amp subwoofer.using a longer run pair of decent RCA interconnects.
- A suitable longer run pair of RCAs permits an easier and likely better place to position the subwoofer.