PayPal, Audiogon and FedEx or UPS offer next to nothing protection to sellers. Your best protection is to document your sale with pictures and videos before the item goes to shipper. For buyers with no feedback, wire or PayPal F&F options only. If they refuse, move on.
Unless your speakers are packed in wooden crate, do not ship via FedEx or UPS. Use freight, may cost bit more but they will get there unharmed.
And lastly, find a way to speak to your buyer. If they appear difficult, walk away.