The floor between and behind the speakers is too often neglected

If you want a more mellow sound turn your speakers around so they be facing the wall. It will also Improve the bass output.

Double stack of tube traps in the front corners,

One third placement of 4 foot tall half rounds on the front wall,

Maybe some 1/4 round tube traps along the floor front wall junction. And again with the full rounds or half rounds on the side walls, and then maybe some 1/4 rounds again, along those wall and floor junctions.

If you have multi kilobuck gear, this may be the best money ever spent.

That is..if you are trying your best to move toward perfected neutrality so you can nail the dynamics and overall tonal presentation ’exactly so’...so you can avoid coloration and then buying gear to offset that. Which is a disaster for sound quality. Error stacked on counter corrective error is ..well.... stop. Just stop.

When it comes to acoustics, always go big, or stay home. Get some headphones or something... :)

This might be $2-3-4 grand but it’s probably the best money ever spent and will outlast all gear.

Importantly, the room is fixed in critical ways which makes you stray toward neutrality, not correction in gear purchases, which is the biggest horror show of an error -- of all. Criminal, actually.

You can diy all of that stuff for hundreds of dollars, not thousands.

ron - ASC is super expensive, GIK on the other hand is far more affordable. :) 

" The floor between and behind the speakers is too often neglected"
I know, I'm floored about that and try to include them whenever I can ... ;-)