Where does fatique come from?

"grammer"

Spelled "grammar".

Stop fatiguing yourself!

Usually from distortions occurring in the mid to upper frequency range.

One of the most common sources of fatiguing distortion comes from individual component's inability to accurately reproduce sharp transients and dynamics accurately. When these occur, the system cannot respond fast enough and fatiguing distortions occurs. Some may find sharp transients and extreme dynamics fatiguing as well even when accurately reproduced because these create the high pressure level variations in the air as sound is transmitted that can stress or fatigue the ear itself.

The problem is much more common with digital sources compared to analog/vinyl sources which is why I believe more find digital to be fatiguing than vinyl.

Planar and electrostatic speaker systems in particular ten to not move as much air and typically produce transients well and do not deliver in genreall deliver the extreme dynamics compared to conventional speakers using dynamic drivers. This makes them often an attractive option for those that may be fatigued by more dynamic designs.

Maggies are well known for being "easy on the ear". They are not fatiguing at all, sound better the longer you listen, and you are seldom inclined to stop as a result of fatigue. These are planar designs that have very good transient response (low distortion there) and they do not move a lot of air compared to conventional full range dynamic designs, so dynamics are generally not as fatiguing either.

Omnidirectional speakers, like OHM Walsh designs, can also be comparatively easier on the ears as well because they do not blast all the sound and the associated high pressure levels in the air directly at you. They tend to fill the room with music instead, more like what occurs at a live, un-amplified musical performance, which enables realistic listening levels with less fatigue as well.

BTW, this is an excellent question. The best way to a pleasant listening experience is to eliminate or minimize factors that cause fatigue. It is something that is not discussed as often as are things like tubes versus SS, vinyl versus digital, detail, imaging, etc.

"fatigue can occur, as has been suggested when one attempts to focus, i.e., listen critically and analyze, for some period of time.
"

So there must be a lot of fatigued audiophiles out there according to this.

I thought listening to music was supposed to be relaxing?