Brian,
But when loudspeakers are given enough power, a system can produce awesome dynamics, with sound that feels so real you can almost touch it.
What musical fidelity says is true, however, what they neglect to mention is power compression in speakers (due to thermal issues and excursion outside of Xmax or linear excursion range of their often cheap drivers)
This means that ALL speakers will compress at higher SPL ouput levels and only "true Hi-Fi" speakers, to borrow musical fidelity's language, will compress very little.
Furthermore, speaker distortion increases very rapidly above 95 db SPL...so not only will it compress but it will sound harsh and perceptively very loud (due to distortion perceived as loudness by the ears/brain)
In practical terms this means that a 500 Watt amp will not help you with a typical audiophile grade speaker that uses $80 retail cost woofer drivers (with limited Xmax and thermal compression characteristics). Again to borrow and reverse their terminology, this is like connecting a Ferrari Engine to a Sewing Machine transmission!
Equating speaker sensitivty and amplifier power to maximum SPL output level is completely academic or meaningless, as most $80 dollar woofers are already compressing/distorting severely at 105 db spl levels!
For example, the best subwoofers typically have way more than 30% THD at 20 Hz when approaching levels of 105 db (the majority are totally off the scale in distortion)...some of the very best will be around 5% THD and the best published specifications, such as the Velodyne 1812, claim 1% THD!
So what is the point of all that amplification?.....nothing if it coupled with a typical sewing machine!