You'll get into a pretty long debate on the subject of mounting an amp to a box. Car Audio guys have argued this method forever. I wouldnt say "never" mount an amp to the box. But if you can build an amp rack or find another location it would be better. If you do mount the amp to the box try not to mount it to the largest flat plane on the box. Wood will flew a bit and its better to keep it on a smaller well-braced side of the enclosure...

I have only had 2-3out of hundreds of amps come back to me that have failed due to vibration. And they were all either very low end or very old amps...

 

mainly its all gonna come down to amp quality.

If your running a standard amp compaired to a higher quality one. the lower one will more than likely fail.

 

i agree on the possibility of debate on mounting an amp to the box. I always have, even with my larger systems, and still have never had a problem. but you never know.