These two suggestions are good ones with some caveats. Styro can crack if you put something heavy on it, like a 50 put on its corner. Shipped on a pallet, it could work. Styro also creates dust as its rubbed in transit and that dust covers everything. Styro dust sticks to the sticky surface of the mid driver and we’ve seen many many speakers come in ruined visually by styro foam used by some packing company. So wrapping the entire speaker in some kind of wrap or giant plastic bag to prevent that dust is a good idea. The cardboard edges are also something we and ATC uses when banding boxes to a pallet so they stay on during shipping. But putting them direct on a
I absolutely would not ship something that weighs over 50 lbs in non factory or make shift packaging. I cannot tell you how many broken ATC’s I see sent to us by Box Bros or UPS local ship it centers improperly packed. Plus broken cabinets are VERY expensive to replace.
Brad