@tablejockey I agree, that getting the room set up to be a very good interface for the produced sound energy is a high importance.
Looking at the OP's set up, there is the possibility such a practice of getting the room set up to interface with the Speaker is addressed.
As energy is always transferred, it is best to discover the methods that can be adopted to transform the unwanted energies into a form that has the least least impact on the quality of the Sonic being produced.
The interest in audio equipment will nearly always lead to investigations about how to eek the betterment, even the smallest of change, if seen to be resulting in a betterment, can end up being sought by certain individuals.
When I suspended my Speaker Cables with a Cotton Thread, they were no longer in contact with anything but the Terminations and Cotton Material.
Did suspending the Cables make a difference? It is not certain, but there are Cables in use that are in free space, and when I tidied up the Systems Cable Loom, ensuring that there was a minimum of crossing over cables such a Power, Interconnect and Speaker, the improvement in the sonic produced was very noticeable.
Again something that can be achieved for next to nothing in monies outlaid, and highly recommended to take the time to put into practice.