Shipping speakers

I've shipped using SEKO not sure if they're in your area. Never had an issue but I always have them strapped to a pallet. 

One other step that I've found useful -- Buy a sheet, or half sheet, of 1/8" plywood at a home center and completely line the interior of the cardboard box, attaching the plywood to the cardboard with a hot glue gun. If you're properly paranoid, reinforce the corners with triangles of the same plywood.

I’ve had damaged speakers, turntables, amps, ..., and all the damage claims except one were rejected by UPS or FedEX even though the package boxes were the original shipping boxes. It didn’t matter if the items were fully insured.
The only one time the claim was accepted was when the seller packaged at a UPS store. A UPS clerk helped packing, and the turntable was damaged, and the UPS cannot but accept the claim.