Another problem connected to the room treatment emphasis is the narrow sweet spot encountered with many of the larger and most expensive tower and panel speaker systems. Even moving from side to side a few inches destroys most of the superior imaging and soundstaging of many two-speaker setups. OK, so the majority of the audio unwashed out there has never heard of the idea of sitting equidistant from the two speakers in an equilateral triangle and thus has one speaker horizontal at floor level in one corner with the other vertical high up on another wall. Stereo purposely mixes some of the left channel signal into the right and vice versa, and then when your pair of speakers are speaking in your listening room they do the same thing. Not only that, but half of the musicians seem to be clustered over just inside your left ear and the other half of them over just inside your right ear.
Some people also hear another cluster in the middle of their cranium.
For many listeners and some types of music this subtle circuit enhances the listening to stereo material. Here is a less subtle enhancement for listening to all these recordings and broadcasts that were never designed for headphones. Binaural recordist Ron Cole came up with this chart which corrects for ear canal resonance and other differences in the spectrum between speaker listening and headphone listening. While I have yet to try this in combination with the HeadRoom circuit, the two should be a synergistic duo. There's only one way to do that.