I have a suggestion. You can ship large items without having to package them using an independent LTL Shipper. You'll get a much better price for your speakers if you can open it up nation-wide.
Several years ago I shipped a large item to big to pack using one of the sites where you ask for quotes. Sorry, it was a while back so I don't remember which one, but there are several to choose from like uShip, Shiply, etc. I found a guy who was already going past me, and my destination, on an upcoming trip. He just bungeed it inside his box trailer and charged me way less than what you would pay to ship via UPS!
Good luck!