I recently shipped a Yamaha M-80, 55 lb unit. I custom build box around units. Large cardboard laying flat, 1.5" min. styrofoam on card board and under unit(with holes for feet and 1.5" wider and longer than unit), unit wrapped in thin 1/8" white foam to protect from abrasion then placed on styrofoam, styrofoam for sides rear and front should rise 2" above unit's top with the front and rear having open spaces for the protruding parts, and the back should have enough open space to contain the cord bundled and wrapped in the thin foam, then have a sturdy straight edge handy to make fold dents in cardboard as you go, with razor knife cut cardboard outward from corners so it will fold up to make box around all nice and snug, the corners will have enough to flold around as flaps which is where the hot glue gun comes in, fold around all coners and hot glue tight while making sure packing is all snug, place a few pieces of cardboard on top of unit to protect the breather slots from denting and use styrofoam only around the perimiter of the top of unit on that cardboard, now with knife cut in the corners up from the top of packing to make the box top flaps so 1st set meets in the middle and the second set completely overlap eachother, fold in 1st two then hotglue 3rd flap to completely cover the top, then fold down and hotglue the 4th to completely cover the top also, the top will now effectively have 3 layers of cardboard strength. Unit is snug and protected. Place that packed unit in a box at least 3" larger in all directions and fill the space with peanuts, and all corners should have 3" sturdy foam V blocks(you can custom make blocks by hot glueing styrofoam pieces together to meet your needs). You will need a large supply of glue sticks, they are invaluble and the cheapest will do. The custom cutting of foam can be done easily with an electric meat carving knife commonly found at thrift stores for $2-4. By hotglueing the box flaps closed and taping the outside makes for a very rigid build. You can hot glue corner reinforcements inside box for added strength.
I shipped the C-80 and T-80 together in a seperate box(lighter weight each), each wrapped in thin foam, then placed together top to top with piece of cardboard between, then packing tape around middle/circumfrence to keep aligned, then tape around sides/back several wraps to hold tight together(no tape around front/back so no pressure on protruding controls or connectors), then custom box and into second box in same steps as done for the above unit(M-80). When I was done and test bounced them, I was satisfied they could've survived a one story drop. But there is always a chance internal parts could fracture(PC boards) or parts break loose. If interior protection is really needed, remove cover from unit, lay in several plastic shopping bags and overfill bags with canned expanding foam isulllation and press down with cardboard so it form fits inside and level with top, alow to cool and become solid/breath out cureing fumes, then reinstall cover and apply note alerting recipient to open and remove before powering up the unit.
Feed back from the last unit I shipped, a Kenwood KM-993 amp: O boy supper nice. and packed to beat all. me very happy. thank you.
Packing well gives peace of mind and a great feeling when report is good. Next time I use this technique for packing I'll take pics n post em'.
Good luck understanding all that, Duguana
PS: I've received several pieces damaged that I purchased through ebay, some even after I pleaded for good packing and they assured me they would. The handling/shipping company handled them rough but they would've been ok with proper packing. When many layers of bubble wrap are used, the corners of units just pop the bubbles when jostled thus rendering the bubble wrap useless and the unit can shift around more and pop more bubbles etc. One that I recieved actually had smashed in rear corner so bad the metal cover was torn some and guts all broken loose, PC board cracks, it was shipped together with another unit and poorly packed so they beat eachother silly. I repaired the unit (Pioneer CT-M5R multi cassette changer)myself first then once it was up and running for a few days without trouble I contacted seller and requested phone comunication, provided photos of repair process through personal email as proof. Seller refunded all shipping costs and agreed to pack with more care in the future(yeah right). The unit it came with was a Pioneer PD-M430 6CD player which worked fine but ended up with some dings. Pics of CT-M5R. I jumpered the PC board crack. I always prefer to try to repair first than to have to hassel with an insurance claim, so far I've saved all.