Ian,
You need to pretend that evil gnomes are going to be trying to damage your pallet with whatever they can get, banging it around in the truck and dragging other pallets against it and scuffing it with forks.
Wrap your speakers in cardboard and tape well. Put them on the pallet and band it tightly. Then wrap it all in plastic, and under the last layer or two of plastic put a shipping label... then when it ends up in Kalamazoo you have some recourse. Put your contact info on the label, or that of the consignee.