I had the same problem, I have a DBX equalizer that wouldn't exactly get too hot, but I used to have my Microkorg on top of it to save space and just like you it barely fit. What I did was get a MDF board sawed in the dimensions I wanted it to be and build a box of it with two open sides (to put the EQ in so that I could easy access the cables and inputs in the back and also easily access the frontside). I made sure the topplate was the dimensions of the Microkorg's footprint and by choosing the thickness of the would I easily have a centimeter to a centimeter and a half on both sides and the top of the EQ.
Since the EQ isnt as deep as the Microkorg I made the footplate the same dimensions as the EQ so I can use the space that saves to put in the stand of my flatscreen computerscreen.
Was kinda easy to do, painted it black so it blends in nice with my desk and it works perfectly. The Microkorg stands very sturdy now and the EQ isnt damaged on risking any overheating. If you still want to consider putting your Microkorg on your amp this might be a solution. I can post some pictures if you'd like to see the endresult?