Friend says he plugged in a K-100SW subwoofer into a system of Yamaha receiver circa 2008 and Quintet SL speakers. The speakers became noisy after that but sound fine without the subwoofer.
This is already a replacement subwoofer after Klipsch support said the first one was likely bad. He may try it at a neighbor's house but wondering if anyone came across something similar? Not sure if the sub itself was working, I'm following up.