What happened to my room acoustics

To add to all of this...if using stands... spikes tightened?...leveling speakers helps? fwiw.

Thanks, but that isn't the cause of the issue. As I explained, the treble dip at 12kHz is most likely inherent to the speakers, while the boosted midrange and mid-bass are likely due to reflections.

I do not use spikes under stands or speakers. Spikes are not ideal decouplers. Instead, I use Moon gels, which are drum dampers, under the speakers. In my opinion, they are far more effective decouplers than spikes, and they also help keep stand-mount or bookshelf speakers level and stabilized on the stands. Based on my A/B listening tests, the bass performance is as good as the SVS SoundPath Isolator, which costs $99 for a pair of speakers.    

Yeah ive heard of people using the moon blobs...ill trust your not on carpeted floor like i am...were i want stands coupled to floor with spikes.Thanks...glw project.

My stands are on adjustable metal screws, securely anchored without piercing through the carpet.  Moon gels decouple so well that the vibration from the bass is not felt on the stands, and the vibration from the ground is not transmitted onto the speakers.

@lanx0003 

If you have a good floor the last thing you want to do is decouple the speaker from the floor. Ideally you would bolt it down to the floor. Spikes are the usual option. Why? Newton's 3rd law. You need a very massive, fixed mass (the floor) to control the reactive forces or the speaker shakes. Play a 20 Hz test tone and put your hand on the speaker. What you feel = distortion. Now spike the speaker to the floor and you will feel less shaking. You might also notice more aggressive bass. I'm afraid this whole speaker decoupling gig is an example of lay intuition. If a floor is so bad that it resonates in the audio band then fix the floor. Most floors dampened by carpet might only resonate in the 5 to 10 Hz range, great for causing footfall problems with turntables but not a problem for loudspeakers.

You might want to consider a MiniDSP SHD Studio. This assumes you have your own DACs. It uses Dirac Live which is similar to ARC. This unit is $1,300 and includes streaming. Benchmark Media Systems uses a Studio with their own DACs and is super pleased with the results. It also includes subwoofer crossovers and bass management.