"Why would anyone want 110db of audio from a stereo?"
Dancing in the cockpit comes to mind.
As a serious answer, it is not that someone with a lot of power available ( I am a classic example) is constantly playing it that loud. Having extra power available ensures that the AC electrical waveform being amplified is not clipped off with the brief high-dynamic range transients.
The electrical signal coming out of an audio amp is an AC signal. It varies with frequency, since it is after all music, with low notes, and high notes. It ALSO varies with amplitude. When viewed on an o-scope the max amplitude capable from any amplifier can be seen, and described at some max VOLTAGE. IF you draw two lines across an o-scope representing max positive voltage, (amplitude) and max negative voltage, (amplitude) you can visually see based on these two voltage extremes that the waveform cannot go past these two max voltage values.
Now say for example you are listening to a classical recording that has some wide dynamic range. You are listening to it through a 5 or 10-watt amplifier connected to a speaker system where the amp and speakers combined are good for up to 80 dB output. There is a long passage of soft to medium loud music, followed immediately by a large crescendo that ends in a thunderous cymbal crash. All of this program material has to be replicated faithfully at the loudspeakers. So say you are rolling along listening to the long soft passage at, oh, lets say 60 to 70 dB, levels ranging from conversation to typical TV sound, The crescendo and crash coming up are maybe recorded to be reproduced at 90 to 100dB at the level you have your stereo set to. You don't have the sufficient voltage, (amplitude) capability available, the crescendo and crash will quickly distort into heavily distorted output at the speakers; there is not enough "rail" voltage available to faithfully reproduce the peak waveforms. To be able to reproduce the very brief loud section of the program, you have to turn your system DOWN for the quiet section, so much so that you probably cannot hear it well... If you had a higher-power amplifier capable of being louder it would faithfully reproduce the crescendo and cymbal transient without clipping. Just because a stereo can get loud doesn't mean it has to. Only YOU can adjust the volume knob...
(In my best Smokey the Bear impersonation)
"Adding to that discussion true RMS power (Root Mean Squared) is the only meaningful measure of power. Peak power is in my opinion not of value. It simply shows how big the capacitors are in the power feed of the final amp. I always want sound that replicates the original sound (low distortion and high dynamic range.)"
Peak power has nothing to do with the size of the capacitors. It has everything to do with what the marketing department thinks it should advertise to look good. R&D, or engineering have nothing to do with sizing caps to deliver peak power. We engineering types wish "peak power" as a call-out would go away. To get low distortion and high dynamic range, you HAVE to have a big amp. By its very definition, high dynamic range requires you have more amp power than you normally use; for the scenario I specifically describe above.
My background? I am currently wear two hats. I am the Marine Product Line Manager AND the OEM marine sales manager for a well-known mobile audio company. I help design and then sell stereo gear to boat builders...
I am a mechanical designer by degree, and have worked in the audio industry since before college. I worked for a loudspeaker enclosure manufacture and designed speaker enclosures for several name brands including Alpine, Rockford Fosgate, Q-Logic, Polk, MB Quart. At one time the car audio subwoofer section in the Crutchfield catalog had a cover page where 5 of the 7 products shown were of my design, all from different audio brands.
I did live sound engineering for many years, although not touring. I have worked with Herman's Hermits, Gary Puckett, Garth Brooks, (way back when; hooked his guitar into a phono input in a club and put the DJ's mic in front of him). Also the All American Rejects, Branford Marsalis, Watermelon Slim, Bobby Rush... Most of this as a result of running festival audio in north and central Oklahoma.
I did my first car stereo install for a neighbor when I was 12.... I guess you can say I screwed up at an early age and ruined a hobby making it a profession....
