All of the above is the main reason why I disagree with bigshot so much.
Listening at home - and at home only - is subject to many limitations - self-imposed ones included. There may not be enough space for the listening room, the acoustic treatment may be limited or non-existant, the power available may be too short, the speakers used could not take available power without severe distortion/damage, etc, etc.
So, there are any number of factors why listening levels at home are usually smaller than listening live - MUCH smaller in the majority of cases. I too have a friend, who would pay for a front row ticket of the symphony - and try to "escape" somewhere in the back after the pause - provided there are any free seats left, of course. He just does not like it loud - even live.
Most audiophiles adjust the loudness according to whatever maximum level their room and equipment will allow. And are shocked to hear acoustic music live - because the peaks exceed whatever they are accustomed to listen to at home - considerably so.
And that is why most commercially available recordings - even of classical music - are SEVERELY compressed/limited. One way or another ... Listen to any piano recording from the mainstream labels - and then listen to piano live, in a reasonably sized concert hall - not closet. Piano CAN get loud - very loud indeed - if the score demands it. And well below 1% available recordings capture this dynamic range - which can be, again, played up to correct SPL , by yet another less than 1% speaker systems. So, even if approximating the real dynamic range/loudness at home is desired, it is VERY hard to realize in practice.
Now, I am aware that the size of the listening room dictates the maximum "supportable" dynamic range/loudness. And that at home, within a tiny fraction of the space volume of the original venue, the loudness can not possibly be the same.
But, this IS head-fi. And such limitations do not apply for headphone listening.
Bottom line : listening at 99 dB is NOT harmful - not if the recordoing has not been doctored ( compressed/limited/mastered beyond death ). Those 99 dBs will be reached for about 1% of the total time - if not even considerably less. With a dynamic range of say 60 dB and above, the average listening level would be around 50 dB - not more.
It is horrible to see what loudness wars have done to the music delivered by digital means. Comparing the rip of the original analog recorded vinyl record to currently available CD of the same recording is not going to put smile on your face - either when looking at the files in an editor, or listening.
I did LOTS of work on analog record playback during the time some of you were glad that I did not post in this thread. And have, as a "collateral damage", been forced to actually learn just how certain analog mastering engineers and record labels handled the task.
There has been ONE vinyl record, which - up to now - proved to be "unplayable"; with the majority of phono playback equiment at least. It is Wagner music conducted by Carlos Paita
https://en.wikipedia.org/wiki/Carlos_Païta - a 1969 recording by Decca, reissued on his own Lodia label in 80s.
https://www.discogs.com/Wagner-Carlos-Païta-New-Philharmonia-Orchestra-Tristan-und-Isolde-Der-Fliegende-Holländer-Die-Meis/release/10689527 A cartridge that can do it justice is anything from the upper thirdf tier of Grado models late 70s/mid 80s ( has to track cleanly at least 90 micrometer amplitude - some Grados of the period went past 110; bass and dynamic range without any hint of compression like most others can not even dream about ) in an arm that mates well with Grado ( not an easy task ).
This recording is phenomenal ... regardless from which point of view. And, it is from 1969 ... - one wonders what went so damn wrong today we are getting such limited in everything scale models of what has been, obviously, possible in 1969.
Needless to say, any amp/speaker combo capable of max 93 dB SPL, has no place in listening to such great recordings. And most will have more problems at the soft end range of this record - room noise floor in most domestic settings during daytime is (too) high, during night time you don't want to start a war with neighbors - even if it is only about 2% of the time.
Use any of the SPL calculators and input your conditions ( room size, speaker placement, listening distance ) to get an answer. There is one not so tiny detail usually omitted in SPL calculators; and that is the polar pattern of the speaker. For a typical box speaker, the polar pattern is ( at least for the lower ferequencies, which actually define how loud it goes ) a point source - which falls off in SPL with the distance SQUARED - it means only one fourth of the SPL available at 1 metre is available at 2 metres. That's why box speakers pretty quickly "dissapear" in large rooms - and large planars, which are close approximation to the line source ( for which SPL fall off with distance in linear fashion ), can with proper placement in fact play loud enough in huge rooms. Dipoles ( most ESLs) do in fact start their real life in 100 and more square metres rooms - and they may never achive the same loudness in small domestic rooms. In such large rooms, box speakers can be FAR too loud in proximity to the speakers - and "inaudible" in the far corner of the room. I am aftraid no calculation can give you precise answer with Maggies - but up to 80 dB SPL should be fine , with any of the amps tested by Stereo Review.
Except that 80 dB SPL is about an equivalent of maximum speed of 40 miles per hour a vehicle on public road can achieve. It is simply not enough for safe driving under real conditions.