Use a freight company, palletize and strap the amps onto the pallet then shrink wrap over it so nothing can be placed on top of it. Fragile stickers can also help. Most importantly double box the amps.
Don’t forget to add ’do not stack anything on top’ stickers on the given package, otherwise they WILL stack stuff on top of your package on the given pallet. One sticker on each side, and one on the top. I’ve seen freight folks destroy $20k pallets of (goo systems) goods that way.
They'll try and deny the insurance claim, if the stickers are not easily visible from any given direction.