Shipping 80lb amps.

Yeah the correct answer is box it well. The original box was only designed to be shipped on a pallette with the other 50 boxes stacked next to it. Also shippers use less care these days. Just a sign of the times we live in. They wear headphones and are just not plugged into the job they're doing.

Don't: double box it with peanuts. Peanuts migrate.

Do: take a roll of HD bubble wrap and wrap it several times around the original box in 2 directions. Then find a 'heavy' box (strong cardboard) that it will fit in. Use foam/bubble wrap pieces to fill any gaps. There will be at least a 4-6" gap from the original box from the outer box. Then write fragile all over it with a thick red marker.

You will not need insurance with this type of packing. But never a bad Idea.

"Instead box it so they CAN'T break it."

No such creature. I once shipped a four foot by four inch diameter x 1/4 inch thick stainless steel pipe. UPS took the challenge and bent it. FedEx lost one of my Harbeth 30 monitors even thought shipped as a pair and labeled box one of two. The humor in it was they knew which warehouse it was scanned into, but could not physically locate the box.

Double box with double wall boxes, palletize, label "no top load" & "fragile" on all sides and insure it to value. Then photograph all sides.

Don’t ship anything in a box or case with a handle on it. With a handle, it’s like a personal challenge to the handlers to see how far they can throw it. I have seen dramatically less damage to items when any handle is eliminated. This even includes a Pelican case in which the handle was sawed off for such a reason. 

Ship on a pallet! I shipped an 85 lb amp via FedEx. It arrived at the buyer with a circuit board detached along with a capacitor. The box was intact with no damage. I guaranteed it was dropped to sustain that much damage.