Fmj, I had a ML-32 for over eight years in my system and it was always left on, not in standby mode, and I have no memory of it ever running hot in any way, including the isolated power chassis.
So, I would have it checked over for a possible malfunction, otherwise this does not make sense to me why you are experiencing this problem.
So, I would have it checked over for a possible malfunction, otherwise this does not make sense to me why you are experiencing this problem.