Good advise, so far, and I agree that proper packaging is the key. One suggestion I would make is NEVER, EVER trust you item to be packaged by anyone except yourself. The UPS store and FedEx Kinkos are not proficient in properly packaging electronics, especially heavy items like amps or speakers.
In addition to some of the other suggestion of wrapping in plastic bags and using foam sheets, I like to wrap items tightly in several layers of "cling wrap". This typical kitchen product clings tightly, won't shift (shifting can cause rub marks) and provides a nice first layer against cosmetic damage.
Also, even with factory packaging like moulded foam end caps, I place extra cut foam sheet inside of the open area of the factory packaging. You can buy excellent foam sheets from a building supply center like Home Depot or Lowes. Don't get the brittle white stuff, get the kind that is dense and has a backing layer on it. It is much easier to cut and does not break up like the white crap.
I also suggest building a complete surround of the product using these foam sheets. You can easily build an indestructable container if you properly cut the sheets so they fit tight and can't shift/move. The item inside will withstand the drop test if packaged properly.
Enjoy,
TIC
(Tom In Cincinnati)
