The problem with using "peanuts" alone for shipping purposes (as is often done) is they have a tendancy to shift around very easily during transport (and especially when shipping heavy items.)
To demostrate this action, place an item like a large steel wrench on top of some peanuts inside a box and shake the box up and down like a salt shaker....
So what did you observe? - Did the wrench end up filtering it's way down to the bottom of the box yet?
This action occurs during shipping and usually exposes a corner of the equipment to the edge of the box and usually results in shipping damage.
(Oh, but how did that happen when I used shipping peanuts inside the box to ship the item... Well, now you know
The item you are shipping should not have any opportunity to move around at all. Peanuts are only "filler" material inside the box. They are not to be used as the "main method" to support items inside the box.
The item you are shipping should be fully "suspended" inside the box using at a minimum - 4" foam inserts all the way around the item. The inserts should not have any opportunity to wiggle around inside the box. The item inside should be packed "tightly" and not move around at all. It should be completely suspended inside the box. Then.... after all that is done, THEN you can fill in the empty space with peanuts.
Similarly, "bubble wrap" is not enough to use as shipping material either. The bubbles can "burst " (again, especially when shipping heavy items or items with sharp corners on them) and this results in your equipment taking the full shock while resting on a flat piece of plastic during the entire transport. That's why it's best to use a combination of materials instead of relying on one.
Styrofoam. - Great for "suspending" all corners of the items inside the box. Think "tight" You can cut syrofoam using a box knife and customize it to the right size to fit your equipment. Places like "Family Dollar" are always thowing this stuff away. It's free!
Bubble wrap. - Great as a way to fill the interior of your equipment to prevent tubes or transformers from coming loose and rattling around inside. Try to leave no empty spaces inside the gear when shipping. Bubble wrap is cheap insurance when used inside a rig or amplifier in this manner. I don't suggest you just bubble wrap a rig several times, throw the rig in a box and call it good for shipping.
That's exactly how things get broken.
Cardboard tubes - (Used paper towel or toilet roll tubes) - Great for protecting tubes. Place a little bubble wrap around the tube, tape it in place using scotch tape and cut the cardboard tube to the appropriate height plus a little extra and place the cardboard tube over the whole arrangement.
Peanuts - Used to fill the box AFTER all the equipment is entirely "suspended" inside the box using foam and / or cardboard inserts to hold the equipment in place.