You have already received good suggestions, and I especially support freight shipping for heavy/expensive items and strapping them to a pallet. I have twice shipped a pair of Clayton M300 monos (almost 100# each) and a pair of Lamm M1.2 monos on pallets using FedEx Freight, which seemed organized and professional as already mentioned. They also seemed logistically superior to their ground/air brethren wrt both timing and locating...I doubt the freight arm of FecEx sends stuff to the wrong city very often.
In cases where expensive electronics are shipped by commonly used shippers (i.e., UPS or FedEx) they should be boxed in the manufacturer's purpose-designed packing - dense closed cell foam specifically shaped to hold the item at least two inches away from the walls of the box is best. You can identify the level of care taken by a company by looking at their packing. Cardboard boxes should be double wall and even if these guidelines are followed, I recommend using a second, outer box that isolates the manufacturer's box by an additional one to two inches. Here are packaging guidelines posted by DHL.
I just received a Hattor preamp that was packaged in its own foam-lined case that the shipper packed inside of a sacrificial outer cardboard box, and it arrived with no issues.
It is Cary's job to deliver new, undamaged amps to you. Rather than taking an active role, you may want to ask Cary, "what are you going to do differently to get these amps delivered to me intact?" Good luck!