I don't have any tip for you but I have same experience with combination Stage & Headrush 108. Whatever I did the sound was extremally boomy and lot of additional tweeking was necessary to get reasonable sound. My quick solution was - sold Headrush, bought Kone speaker (put it into the cabinet) and class D amplifier. And everything is ok now
Thanks for your comment. Once I receive the power amp from SD I’m hopeful that the Kemper kab will sound tremendous ??