Kicking in a bit late on this thread (I have not tried the QOL yet) but Setonaudio's mention of room problems, odd shapes, etc brings up a good question, for me anyway.
I have one of those difficult rooms (open side, other issues) and I'd put a McIntosh MEN220 into the chain more than a year ago and it solved "the problem" (loss of upper bass signal). So, the MEN220 was a gamechanger for me. But because it is a sort of (for want of a better word) "processor" I am wary of what might happen if I thrust the QOL in there.
I do get the idea that I can try for free, of course. Any thoughts? Anyone else in the same boat?