I read the TAS and 6moons reviews and decided to give it the 30-day trial. To my eyes, it looked like the fundamentals are identified (more or less) by filtering different frequency bands out, then passing each through a set of phase shifts (like delays) and adding it all back together with a pass-through copy of the original signal for each channel. The end result would be similar to the reverb that sound engineers use to provide a matching "space" or ambience surrounding each close-miked voice in the final mix.
In other words, it takes that clean, noise-free, transparent and distortionless audio signal that we audiophiles have worked so hard to achieve in our systems, and adds in small, distorted copies of the original signal.
And that's more or less what I heard when I tried it in my headphone rig. Each voice or instrument had its own "space" around it. Each one sounded as if it had been recorded in its own soundbooth. Terribly incoherent on headphones.
And that's what my ears heard when I tried it my speaker rig. So, a well-recorded solo piano normally sounds as if it emanates from a point source about 6 ft behind and between my speakers, with slight shifts between high notes and low notes, like a real piano. And each note is crystal clear, with natural attack and decay and sustain.
With the Qol, the piano sounds much more solid, spatially expanded to a real-sized source. And with every acoustic recording, each voice or instrument no longer sounds like a point source, each seems to have physical size and presence.
So for me, it is a distortion device. But when I pulled it out of the system, my wife immediately said, "What changed? Please put that back. I like it much better that way." Do I need to explain that if my wife wants to listen to my speaker system with me, I'm all for it?
Of course, when I want to listen alone and hear beautifully transparent and distortion-free music, I use my headphone rig.