i don't see why everybody worries about vibrations from mounting an amp on a box. if any vibrations are going to damage the amp, the vibrations from driving the car will. more than likely hitting bumps and potholes will shake your amp more than your box can ever allow it to vibrate, and if an amp can't handle road vibrations, its a shitty amp anyway
Thats not really correct... your car vibration due to the road doesn't shake the amp 20 - 80 times per second like box vibrations can. A solder joint isn't an extremely strong physical connection, no matter the quality of the amp this remains true.
And again, it's not extremely common to vibrate an amp to death -- but it CAN happen, so why not spend 10 seconds and put some rubber feet under the amp? As I said before... not many people will short out their power wire -- but we would call them dumb if they didn't run fuses.
I always mount my boxes to the vehicle very securely. The point is to transfer as much low end material to the vehicle's chassis/body as possible. So Im just not seeing that an amp rack mounted right next to the sub enclosure is going to have all that much less vibration than if it was mounted securely to the box.
Im not arguing against prudence, if you are worried then use rubber feet. But in reality, little rubber grommets aren't going to stop much vibration anyway. Do it if you are concerned though.