Causes of long term listening fatigue?


I like to listen to music continuously for hours mostly at low volume levels. For me therefore, it is important to have a setup that will not cause any listening fatigue (lf).

Now I am looking for a new speaker setup and I wonder whether people could comment on the following aspects:
1. is 5-ch more susceptible to lf than 2-ch?
2. are there quick tests so that one can determine whether a given speaker will tend to give lf? I ask this because in a shop it will be difficult to assess this due to lack of time and differences in acoustic environment.
3. Which speakers do you know in the price class $3k that do have lf problems and which ones can be recommended in this respect? (difficult question, I know).

Thanks for input.
Regards,
karman
LF is caused by odd-ordered harmonic content in the signal, usually harmonics of the 9th order and beyond. These harmonics are emphasized by the use of negative feedback in amplifiers and by non-linearities in transistors (and to a lesser degree by non-linearities in pentodes).

IOW, LF is usually not caused by speakers alone. To reduce odd-ordered harmonics, one will have to use a tube amplifier with little or no feedback. Such an amplifier will need a linear impedance curve from the speaker, so if low LF is your main priority, then you now know what you have to look for!
Brightness caused by speaker and/or room is numero uno. Also hardness and grain I cannot deal with anymore. So I feel any component or possibly a combination of components can cause LF.
You are correct- the reason is that our ear/brain systems are tuned to accept odd-ordered harmonic content as *the* loudness cue (read: Listener fatigue) in anything we hear. Anything that causes an emphasis to those harmonics results in listener fatigue.

Bright sounding electronics get that reputation through the negative feedback they use. Speakers may get that reputation for a variety of reasons, not the least of which is that improper relationships between the amp and speaker (transistor amp on a high efficiency speaker, for example) can cuase the speaker to become shrill when it is not normally.
I agree with the electronics as the starting point to address LF. Two months ago, I replaced my modified Music Hall CD25 cdp with an EAD CD1000 series III cdp. I changed nothing else to include my listening environment. The sound was much easier on the ears. In my system, the CD25 sounded very detailed, almost too detailed. The CD1000 is much, much smoother sounding, with a warmer feel.

Just my opinion from a very recent experience.

Mike