Why magic at 80 db?

Many good posts. The better the system with less noise and distortion the better it will sound at both low and high levels. And everything in between.
I'd say, yeah, my system too sounds best at probably 70db-80db. Go louder - significantly more distortion, go lower - lose something. But my amp is not so good; with better amp it would be somewhat different. Still, the figure of 80db sounds about right to me.
Software matters, that's for sure.

Rodman99999-Thank you very much for the website digido. A wonderful lesson in mastering and re-mastering regarding loudness levels. A bookmark for sure.

To follow up, here's some extended discussion from a mixing/mastering forum concerning how to set an 83db "reference level", how fatigue plays out at that level, different opinions regarding the potential for hearing damage based on time of exposure, etc. You guessed it, there's a forum for everything. If you're interested, you can also find extended discussions of mastering styles and theories, the benefits and evils of "compression glue", and all manner of other stuff that goes into the decision tree behind any given track. Personally, spent a bit of time digging into this stuff recently, but ultimately decided that ignorance is bliss on this one. (Figure I enjoy sausages a whole lot more for not knowing how they're made, either. But that's just me.)

That's how they are made...ah, forget it. I wish I could too.

I've been a professional musician for many years...guitar, loud bands, live sound mixing...blah blah blah...I was sitting in a movie theater a couple of years ago (rare for me as I usually wait for films to be available for home) waiting for the film to start and I was ASTONISHED at the high sound level of the previews...wow. I looked around thinking people must be stunned...and the crowd seemed oblivious. Amazing. The features seem a to run less hot, but still...wow.