First cordial discussions, Paypal dispute, notify A’gon and IF after all this a successful resolution fails and things get UGLY.
The picture that MAY be emerging, worst case scenario, is that this individual knew exactly what he was doing, selling defective speakers that he obtained cheaply from his place of employment. Thinking you are a newbie and won’t notice the bad tweeters. If he gets really nasty about this, maybe the best course of action will be to go over his head directly to his place of employment.
Many years ago I bought an expensive pair of monoblocks on eBay (before it went totally to sh*t) advertised as and I double checked with the seller that they were as new, pristine, never repaired. Someone I knew had purchased an item from this guy before without a problem. One of the monoblocks ran scary hot for an A/B amp, the case had discoloration signs of having been overheated. Opened it up and saw a hack of an amateur repair job, totally obvious. Wrote to the seller who lived on the other side of the country and his reply was "tough luck, you bought it". This particular character had used his (nonaudio related) work email in his correspondence, and I said I was going to call the president of his company, who I named (thank you internet) telling him I thought his company was guaranteeing the product he was selling since he was using his work email which had the company name in it..
Money paypaled back to me literally in 20 seconds. The next email from him was that I was a prIc*, all I had to do was ask for a refund in the first place, which of course I had. What a jerk.
Unfortunately, I did eat the shipping cost back to him. I was just so glad to get a refund I failed to consider shipping back.