I'm getting lots of pops. I have a Yamaha SWK-W10 wireless kit attached to the subwoofer which gets its signal from my YSP-5100 sound bar. What is most likely the culprit? the SWK-W10 unit, the cable, or the subwoofer?

Have you tried connecting the sub directly (with a cable instead of the wireless setup) as a test? Do that - if the pops go away, its the wireless. If not, could be a problem with sub or the receiver. Your GoldenEar dealer should be able to help you sort that out.