A few thoughts.....
I agree with Mark that the styrofoam alone would have been sufficient,
if the package did not fall off a convertor belt or otherwise suffer a significant drop during shipment/delivery.
So, why do I pack amps the way I do you ask?
Other than the fact that I have to anticipate the worst (i.e., a significant impact event) when shipping with UPS and FedEx.....
1 - The dense styrofoam insulation I line outer boxes with is to reinforce the outer box strength and provide a strong and durable first line of defence against any external item puncturing through the outer box's wall. I do not look at the dense styrofoam as providing any cushioning whatsoever. It is very hard.
2 - The medium density styrofoam I line inner boxes with is to (a) reinforce the inner box strength, and (b) provide
some cushioning to the item being shipped. For example, if this package was dropped 5 to 10 feet, the amp would crush the medium density styrofoam somewhat, but would not break through it.
3 - Bubblewrap is great for protecting a guitar amp from getting scratched during shipment but, with any significant force exerted (e.g., in a large and jarring drop or fall), these "bubbles" will all pop and will not provide much cushioning at all. Bubblewrap is great for providing a cushioning effect for lightweight items - not something that weighs the better part of 50 lbs.
4 - Packing or kraft paper is great for filling voids with lightweight items, but if a heavy item suffered a fall or drop, the kraft paper flattens out like a pancake very quickly, and remains that way (e.g., for the rest of the package's journey). It
does not provide sufficient cushioning for heavy items.
5 - I always put the peanuts between the inner and outer boxes, as these are the "shock absorbers" in the overall pack. If this parcel was to fall a few feet, as already outlined, the styrofoam and bubble wrap wouldn't provide sufficient cushioning. Packing peanuts are designed to compress on impact and then return to their original form. This is especially advantageous if the amp is to continue on its journey after suffering the fall. As such, the peanuts are the primary item that would absorb the impact from a fall. I also always pack the peanuts tight, to ensure the inner box does not move around during transit.
My approach is largely inline with the guidance on UPS website:
http://www.ups.com/content/us/en/resour ... w_to2.html
I also agree with Mark that the best protection is the stiffer foam used by amp manufacturers. The problem with this foam is (a) it's next to impossible to find as amp manufacturer's typically have to have their foam inserts custom made by a foam injection company, (b) it's extremely expensive and (c) it's AWFUL for the environment - worse than any other packing material described.
At the end of the day, I agree with Mark that peanuts are annoying. I just do not know of another packing material that will economically fill the place of what I use the peanuts for.
Finally, the direction this thread has taken is hilarious. I post these threads to (a) provide a purchaser with comfort that his/her item was packed properly and (b) to evidence the pack job in the event of a claim. UPS or FedEx could never argue this package was not properly packaged. I would take them to small claims court if they did and can guarantee you that no judge would find in their favour. I went over and above in protecting the item being shipped and any damage resulting from shipment would clearly represent failure for UPS/FedEx to exercise an appropriate duty of care (the laws of contract and torts both cover this legal argument).
Carry on!
Luckily, it arrived at the same time to the store as part of a three amp shipment. Upon opening the other amp boxes I noticed the same thing, broken tubes! I was able to make one good set of tubes between them and got the glass cleaned out of one Dual Rectifier which I still have today. I can't believe Mesa ships their amps this way 
