My solution was an easy to build, self-made amp stand. It’s made out of 3 wooden boards and 4 movable angles. Since I use this construction, I always can hear myself properly, which makes playing much easier of course. My engineer (on live gigs) does not have troubles anymore with the sometimes extreme highs, because the speakers look upwards now. And, most important, I can use any of the three amps I own, without changing the look or diminish the worth of my amps by drilling holes.