A hifi shop owner that got a fat stack from me recently knows how to make speakers sing. I used to stop in monthly and listen and he could take a pair of large floor standers and have them sound like a live band one time and the next visit, in the same room, same wall have them sound like mini monitors. I’ve heard him do it with every new feature speaker he demonstrates.
I asked him how he does it and I get a smile back for an answer.