Listening fatigue

One of the most closely guarded secrets in all of audio is why the distortion rises so much as the volume is turned up. Now, I'm not saying that some of the distortion we hear at higher volumes is produced by distortion in the speakers, distortion in the electronics and/or distortion produced by room acoustics anomalies such as comb filter effect. The problem is that even when those fairly obvious potential causes of distortion at higher volumes have been addressed there is still a significant amount of distortion at higher volumes. It's a little bit analogous to the background microwave radiation - we can eliminate all the other potential sources of noise in the universe, so the residual noise must be from the Big Bang! So, where does this distortion come from, this distortion that's not related to the audio system electronics, or the room acoustics, or anything in the audio system cabling, or house wiring? Hint: it has to do with why the sound gets better when all telephone books are removed from the house. And why the sound gets better when all CDs are stored Vertically instead of Horizontally. And why taking cell phones out of the house improves the sound.

Ditto the early reflections. Added bonus: by minimizing early reflections later reflections are minimized geometrically. Minimizing corner reflections and slap echo is also important. But I would avoid Sonex like the plague.

Comb filter effects (time domain errors) can be blamed for a lot of the distortion as the volume is turned up since the comb filter effects in the room are a function of the sound pressure in the room. Isolating all components from vibration induced distortion, use of tube dampers, damping CD transport, damping capacitors, colorizing CDs, demagnetizing cables and CDs, suspending cables, all of these things will reduce distortion at higher volumes. Ironically, while digital promises huge improvements over analog for dynamic range and signal to noise ratio, off the shelf digital frequently sounds compressed, noisy, distorted, not to mention thin, tinny, threadbare, two dimensional and congealed.