"Pace", it's importance for enjoyment?

Viggen makes a very good point about the low frequencies. I have a hunch that all frequencies effect PRAT. I have noticed in the past that some of the signal tubes that I use which have anomalies (dips and peaks in roughly the 60hz-300hz range) also do not sound that great throughout the spectrum (general sound, not PRAT). Because of this it would seem that the low frequencies are effecting those frequencies higher up and I would assume that this would also work the other way around (the tubes by the way test fine above the 300hz range). I would guess that this problem in the low registers causes some type of distortion or cancellation effect to harmonics (perhaps even attack and decay) in the higher registers. Most musicians (especially guitarists) have first hand experience at creating such effects in that if one hits a harmonic on one string and then bends/pulls a note (on another string) to and away from the original tone, they can achieve all sorts of things from oscillation, to boosting the harmonic or even canceling or deadening it. My guess is that if one area of the music is not being reproduced properly, then that area can drag or distort other areas.

Some very good points are emerging now, or at least headed in the right direction in my opinion. Such as the observation that mini-monitors tend to have good PRAT (small rigid cabinets not storing much energy). I will just add one observation.

To get between the transistor radio and the sound of the real thing, there seem to be two divergent paths (probably many more, but I am simplifying in order to make a point).

One path is the PRAT path. The gear that follows that path is exemplified by Naim and Linn. Their low-end gear appears brash and fatiguing, but manages to maintain a decent sense of the PRAT in the original performance (systems with good PRAT only have it with suitable recordings of good musicians).

The other path goes the "sound" route trying to make the sounds close to the sound of the real thing, but sometimes embellishing a wee bit to cover over the deficiencies - with the emphasis being on tonality and dynamics. The problem with this second path is that with modest systems PRAT is usually very poor and music becomes boring quickly.

At the top end of the Naim-type gear and the top end of the "sound" route the paths converge again. The reason for this, I theorise, is that the objectives are now being met by both "schools" through sheer accuracy of resolution of detail and elimination of smearing, while maintaining dynamics.

The paths in between merely make different compromises. I agree with Dan that the transistor radio is distorted, and that low-end systems with good PRAT tend to emphasise transients in a certain way - thereby looking after rhythmic cues better than they look after tonality. But the rhythm in the music is not created by distortion. You can still hear the difference between a group that is "cooking" and one that is not. The issue is that a certain kind of compromise is being made.

Ken, I probably made a pig's ear in attempting to describe the separate issues of pace, rhythm and timing and so please correct me where I was wrong. Personally I do not listen for those three things independently. But, as stated before, when I evaluate a component I do not tend to objectify the sound in the way that Harry Pearson does, except initially in order to identify "sound" issues that may become annoying over the long term. My final decisions are made by forgetting the objective stuff and just seeing if I am swept away by the music.

Redkiwi, I like your final test of being "swept away by the music." My wife consistently talks about "the gestalt" of the musical experience whenever we listen critically together. And I agree. The overall experience is what I ultimately listen for - if the experience as a whole doesn't result in being "swept away by the music," it is readily apparent that something is missing from the system. In our case, though, we tend to start with the overall experience, and then objectify to make sure we understand what is causing the good results. If a "new to us" system is not giving us good results at that gestalt level, we tend to simply move on and not expend any more energy on it.

I think we're kicking a dead horse now

Whinee!!!