What the ship just happened?

Unless you are going to keep this forever, send it back. It is damaged and you don’t have the oem packaging, 2 of the highest issues that buyers look at when buying.

I hope you took a picture of the amp on your porch. I had a large piece of art that was damaged by ups and I took pics of the torn box the way it was delivered by ups. I submitted a claim and in the end, ups had to pay $2000 for a new frame, luckily the art work itself was not damaged.

Like fraud, I see more package damage.

When I buy something, I make it clear to the seller that both insurance and double boxing is required. I will be insisting on 'signature required' from now on. I am willing to pay some additional $ if the buyer asks, I may even offer to. I figure a little extra when deciding to buy. To me, now, it's about preventing disappointment.

I mention to the seller, that any damage claim in the USA will likely be denied if the item is not double boxed.

The insurance claim must be made by the seller who both packed it and purchased the insurance. Much better to pay a bit extra for double boxing than wait for a damage claim.

Then we have to deal with shipper's indifference in the entire process. Any package damage, I photograph the box outside of my house, one with the truck in the background if possible. Keep in mind, photos are time dated as are the shipper's drivers records.

Then I open it, hoping for the best.

Air pouches, bubble wrap can all be 'crushed' inside the box, allowing undesired movement. Some non-collapsible materials are needed to prevent that.

I believe @akg_ca covered how best to protect yourself. Wait until the object of your desire is offered with OEM packaging and offer to pay for double boxing. "Fragile," This End Up," and "Heavy" stickers help as will adequate insurance. "Signature required" helps but only if you catch him first before he drops it on the porch.

If it makes you feel any better we've all likely had this happen. When I lived in S. Florida, I bought a turntable which UPS promptly left on an unprotected porch during a 6 hour rain. Drenched was an understatement and nothing was the seller's fault; it was all on UPS.

I always request the seller use Fed ex and then I have the package delivered to my nearest Fed ex store, this way when I go to pick it up I have the Fed ex employee open the box and we both check the contents for damage and if any damage is found I refuse delivery of the package. This way there can be no doubt about when or where the damage occurred, I have never had any problems with this method of delivery, and it assures that everyone's bases are covered.

One BIG no no is never just wrap a big amp(or any heavy piece of equipment) in just bubble wrap. The first time it’s dropped all the bubble wrap pops and your protection is gone.
I worked at an audio company for many years where we’d get in units to be repaired. We’d go through great pains to describe how to pack equipment when sending it in. Use hard foam insulation cut to brace the unit and double box it. There was always someone that didn’t want to go through the work and cost of doing it right and would bubble wrap an 80 or 100 pound amplifier and stuff it in a barely adequate box. The first time UPS or FedX drops it all the bubble wrap pops and it’s down hill from there. We’d get the box with the face plate or binding posts sticking through the side of the box all bent up. The delivery companies will many times claim insufficient packing and not want to pay for damages. The customer would almost be in tears when you tell them it will takes several hundred dollars to repair the shipping damage little lone what they sent it in for. And the chassis will never look the same.
We’ve actually had customers say they saw the FedX or UPS truck pull up to they’re house and roll a 100 pound amp box off the back of the truck dropping it all the way to the ground. The customers response was to decline delivery in most cases.