I have found that styrofoam insulation works very well. Many speaker manufacturers use it. It can be cut to size and does not shift like packing peanuts.
I purchased a 6 pack of 6'x12"x2" for a couple of buck at Home Depot. It's especially good to use for heavy items as it does not shift and can be cut to exact shapes.
For wrapping components, I use clinging plastic wrap (kitchen). Again, it will not shift/move and provides a nice barrier around the component/speaker to keep it from being scratched. I just tightly wrap several layers completely around the piece. Go across the unit both long-way and short way to insure coverage.
As a third item, bubble wrap is good, but expensive. Do not use packing peanuts/crushed paper as the primary packing material, as it will shift and compress under load.
Whatever you use, slightly overpack the box to insure complete protection in case of settling.
Enjoy,
TIC
