Onix A-120MKII Gets hot fast.

6-8 inches is sufficient. Just not on top of each other....

Did it just start doing this? How old is the integrated amp? How old are your speakers?

There could be many reasons why your amp is over heating. The idea of using a different pair of less demanding speakers is a good one. Without taking it in to have someone check the idling current of the output transistors, it's really just a guessing game at this point as to what the problem is. Make sure the heatsinks are not being covered and there is plenty of room above and below the heatsinks for convection cooling.

I would suggest you not place anything on top of the amp. Having anything digital placed on top of a piece of analogue equipment or vice verse is a really bad idea from a sonic perspective. Digital noise is pervasive. Put your digital equipment off to the side and try not to stack anything on top of each other.

My Pleasure....Enjoy.