How loud is loud?

Zavato, I agree with your assessment of loud. And I DO enjoy lots of music approaching those levels, or just below; that's where a good system can reproduce the energy of a live performance. I ensure that I'm not disturbing anyone, and carefully limit my exposure to such levels (I'm not a high-hours daily listener). And music rapidly becomes very unappealing as you push beyond this level.

My problem with systems that do low levels well is that they're usually the result of a modified response curve that complements our own hearing's non-flat response curve at those levels -- the Fletcher-Munson curves are oft-referenced here (though they may not be very accurate). That's not a route that I prefer; I like gear that yields fantastic realism at loud levels and is completely non-fatiguing -- so in most cases bright sounding gear doesn't gel with me.

Yes, if you experience any fatigue and/or loss of hearing sensitivity after a session, then it was definitely too loud, and care should be taken to not repeat those circumstances. If you ever experience ringing, then it was WAY too damn loud, and permanent hearing damage may have occurred.

85dB is the threshold of damage only if you're listening to that continuously for several hours a day. And this threshold probably varies quite a bit by individual. For reasonable listening sessions, this level is quite safe for most folks.

Anyone near a city and/or with yappy dogs will experience sounds that exceed 85dB several times a day.

dB/W/m is an efficiency spec. Not a "how loud is it" spec. That's what dB alone is for. You're grappling really tightly onto an incorrect argument.

It's a point but it's not a relevant point. Wrong details like this drive me crazy at work! Distance would come into play if we were discussing the power required to achieve a certain SPL at a given seating distance. But that's not this thread -- plus that would require consideration of additional variables, and the math inevitably gets fuzzy when room boundaries come into play. This thread right here was SO simple; dB is really ALL you need, and why oh why do you/we audiophiles have to inject chaos and confusion into something so perfectly clear-cut!? :p

Tls49:
Actually, that is the sensitivity spec. And yes, I know many seemed
to be confused about this, and even some manufacturers list it as efficiency,
however here is the difference, Efficiency vs. Sensitivity.

Ah, excellent point. Thank you for correcting me! It should have been obvious that efficiency is in %. You got me!