tcutter - Great info and clearly communicated! Just to add to what you've said so far, I thought I'd add: "For better stereo sound quality - is there an order to treating your room?"
Early in my audiophile journey I thought frequency response was "King," meaning I'd fuss over speaker/chair location for the smoothest frequency response I could achieve while ignoring the room's impact on sound quality. I wasn't even remotely interested in decay time or knew much about early reflections. In time, I began to acquire bass traps, made polyfusers from Sonotubes and a large wooden Skyline diffuser that weights about 200lbs. I'd spread these out around the room but it was never based on much science or a proven methodology.
I couldn't help but wonder if there was a hierarchy or order to applying treatments for better sound.
And it turns out there is! So, before you go waste your time like I did, you might wish to give this room treatment sequence a try. As the two slides I made attest, start with what you hear first and work outwards from there. So, begin with reflections between the speaker plane and your listening position - early reflections for 0 - 10ms. Then handle bass decay times, then mid/high decay times, and frequency response last. This order helps minimize back tracking and having to re-do work already done.
