Just to add my experience here. Oddly from what has been said here, we used FedEx to pack and ship an amp. They did not pack it at all, just took the box we gave them and shipped it. The amp flew around inside the box and of course broke. It was covered by insurance paid for until FedEx said ’we don’t offer insurance anymore’. Claim ignored and denied. Stuck with a $1500 paper weight. No recourse.
My manufacturer has a similar experience with a pair of hand made horn speakers, he explained: "The speakers were returned badly damaged from shipping the crate was stacked and compressed. One cabinet was crushed and one of the horns damaged...plus internal damage on both speakers. The stands were unscathed."
Let me show you the original crate used...
Berlin Type R speakers packing
On the other hand, I have received large horn speakers in Kubox boxes, that were safe and sound.