The standard rubber feet that are attached under the speaker cabinets. Is there some kind of locator plate that the feet can lock into when stacking units? It doesnt need to be deep just enough to stop them moving about (which they do even when rachet strapped together). any ideas? Ive looked before but cant find anything suitable, or even know what they would be called. I've seen that some people use a router to make a sunken area a few mm deep on the top of the cabinet but Im reluctant to do that.
If you don't want to router out a small recess for the feet sit in here are some surface mount stacking feet.
https://us.tchweb.com/collections/rubber-plastic-feet
Look at the stacking foot pairs.
https://us.tchweb.com/collections/rubber-plastic-feet
Look at the stacking foot pairs.
