Eldartford made some good points about distortion, power levels and perceived volume. If one looks in the archives, you'll find that i've always been a BIG fan of "dynamic headroom" in all aspects of system operation. Stressing any part of the system introduces some form of distortion and that added distortion adds apparent volume.
When a system has reached the point of having a high level of dynamic headroom, one can listen at phenomenally high levels for extended periods of time without it sounding "all that loud" and / or experiencing "listening fatigue". This is not to say that i would recommend making a regular habit of this or that everyone should strive to achieve such things from their system, but personally, i find this a very desirable trait. I also found that when i had achieved this level of performance, my listening levels had actually crept up on the average. I know that others here have experienced and shared similar vantage points too.
Having said that, i find that certain recordings have what i find to be a "proper" listening level. Not everything was meant to be played at roaring volumes, nor do all recordings sound best as "background music". A good recording sounds best at the appr listening level that one would encounter if listening to the performers at a live event. Obviously, that volume level will change with the size of the venue, one's listening position, the acoustics of the room and volume of people in attendance, etc... Just as we all have personal preferences in volume and seating positions at live events, i'm assuming that also applies to how we listen to and have our our systems set up at home too.
Other than that, Alpha 03 also made some very valid points. What we are discussing here is the ability ( or inability ) to generate clean SPL's. Due to different levels of loudspeaker efficiency and how they individually dynamically compress the signal, room loading characteristics ( yes, ALL rooms "acoustically overload" at some point ), the ability of the amp to load into and control the speaker system, etc... all add up to what we hear and experience. Like most things, it is a complex subject with a lot of variables involved. Sean
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PS... One can run "straight pipes" on a Harley and have them sound "quieter" than a "race tuned" but muffled "rice rocket". Once again, this all has to do with acoustics, how we hear, the tuning of the exhaust system and the resonant frequency that the tuning occurs at.
Higher spl's or "louder pipes" don't necessarily make more power and in many cases, they actually make LESS power over a wider bandwidth. This has to do with the volumetric efficiency of the motor and the flow velocities involved.
As a case in point, my vintage Harley with straight pipes is measurably quieter ( and less annoying ) than my friends much newer "highly modified" Honda that has "racing mufflers". This happens for the same reason that i can hear "rice rockets" revving up to 10,000+ rpm's several miles away, whereas the noisy "blat" of a poorly tuned Harley only makes it a few blocks. This has to do with the volume of air displaced ( bore & stroke vs rpm's ) and the tuning frequency of the intake / exhaust system.
Much of this has to do with acoustics and the way that our ear / brain processes information. This is why the government chose to use higher frequencies for use in our "emergency sirens", not the less offensive but potentially equally "loud" low frequencies. It is for this same reason that many people prefer to listen to a "soft, warm & smooth" sounding system as compared to a "more forward" and / or "bright sounding" system.
Different strokes for different folks.
