F5m kit

A problem like that would drive to answer no matter what it took. I have been known to use 1/2" angle iron in cases where I wanted to stiffen a panel. Top and bottom covers especially. I would look for a way to do this in a case such as this as well. Sometimes a thick brass bar that fits is all it takes. Drill 6 holes for #6 bolts through the panel that needs the support and thread the brass bar. get mean.
 
If possible, perhaps brass shimming strips may help. This is a real problem, but once you get the thickness correct, you can go from there even if it requires the sanding/grinding of a thick piece of metal to get the exact thickness needed to compensate for this. It can be a lot of work sometimes though and shouldn't have been a problem in the first place.
 
I am running them with twin remote 300VA PSUs.

Sounds simply fantastic! 🎺🙂🎸

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