Quoted from CashMoney:

manadams I had this same issue with a couple of PSW10's that I had purchased from Amazon a few months ago... Amazon randomly had a huge price cut so I jumped on it and purchased 2. Got the subs hooked up using the pinnovators kit on my Spike 2 games and was getting feedback just like you. It has nothing to do with the alligator clips. Un -clip them from the sub but leave the sub powered on and you'll notice that the feedback is still there. Its the actual sub thats defective.
I ended up returning both of the subs to amazon and claimed them to be defective. I purchased 2 more a couple weeks ago (same model/brand but higher price) and I have no issues or feedback now.
My best guess is that Amazon got some refurbished/returned units and price slashed them to get rid of them but this lot of subs was obviously defective and they didnt say anything or test them out... super shady. I would return them if you can.