Rethinking Listening Fatigue

Listening fatigue to me has always been a sure sign that something was wrong with an audio system.

It is a useful test of a system, because it is not always immediately apparent - a fact which has undoubtedly helped Dr Bose get rich.

I have always thought fatigue was mainly a product of digital, overly bright tweeters, and/or a sonic signature that puts too much emphasis on "resolution" and not enough emphasis on high quality midrange.

But lately I am wondering if I have been oversimplifying things.

As you can see in my system link, I am using a pair of ATC SCM 7's with a pair of Behringer amps used as monoblocks for my desktop and PC audio.

Recently, I have added a Hagerman Technology USB interface box, which goes into an Audio Research DAC 5.

To my ears, the ATCs have a slightly laid back, non fatiguing sound typical of many English products which suits my tastes just fine, particularly for very nearfield listening.

What is curious, however, is that I am starting to realize that this system sounds really different depending on the volume and/or the time of day.

At times, this little system sounds wonderful. I feel I can listen to it for hours, with the speakers < 3 feet away from my ears and in many ways, I enjoy it more than the big system.

Detail for both music and movies is very clear and I have especially noted that I am better able to discern dialogue with these speakers, without ever feeling like the sound is too "etched' or embossed.

At other times, however, I feel quickly fatigued and suddently overwhelmed with an unpleasant this is way too loud, the music is congested and I must be bothering my wife sensation.

No one I know has ever described ATC monitors as fatiguing, so I am starting to wonder:

1) Despite relatively high power of the Behringer amps in a monoblock configuration, is it possible that they are overdriven and distorting at not terribly loud levels?If so, would this type of distortion, rather than overly hot tweeters, be a more obvious culprit for fatigue?

2) Or could grunge in my AC also contribute to listeners fatigue? Would some of you recommend a line conditioner rather than an upgrade to the amps for this desktop system?

The fatigue I am trying to describe always manifests itself as 'this is uncomfortably loud' sensation.

Thank you for your thoughts and comments on this and the topic of listeners' fatigue.

cwlondon