A couple of months aga a business acquaintance asked me about building him a "system" for his man-cave.

Well as to not scare him off over price, I recommended him to pick up a pair of inexpensive speakers, a Bluetooth amplifier, and a 15" subwoofer from Parts Express for maybe $500, probably less.

My thoughts being that he wouldn't have sticker shock and if needed, later on down the road I could build him another pair of speakers to really make it sound better.

Fast forward to today with me driving up to his place almost to Peoria to listen to what he had.  I also took my garage speakers along to give him a taste of what was possible.

His man cave/ shop was absolutely stunning, very well done and tastefully decorated.

Anyway we played his system and he told me that it was a little disappointing to him. I then put in my Garage Rockers and the sound was easily 25% better, you get what you pay for with better drivers and better construction.

I asked him what he thought about it then and he said that it needed to be louder.

I measured the room and it was pulling 102dB! The sub was rattling the stuff on the wall noticeably!

He finally told me that a good sounding stereo to him was rock concert loud.

So I guess Loud=Good to the average man on the street.

I guess I should be looking at sound reinforcement type gear for him.

 It's comical isn't it? For decades we all have been hearing 'Bobs new stereo' that can rattle and shake the windows. For myself, I will admit that I do listen loud even these days, and to be honest, it isn't just about my aged hearing. It has often seemed that many speakers don't really sound as good at a lower volume and must be turned up to get what you would appreciate for performance. I recently have moved to a tubed integrated amp, and fortunately I have noticed already that the volume doesn't have to be as high as before. This is closer to what I need to accomplish.
It is a mixed bag, this volume stuff. A room saturates as well as the audio equipment that is producing the music. I rarely if ever get to that volume level, but I do remember this to be part of the problem.
Unfortunately, I also find that recordings can be too soft until the volume is ramped up and then too loud after that! Classical can be one of the hardest cases to balance for me. Piano as well, depending on the movement being played. Midnight Sonata is wonderful followed by a FFFF demonstration following that piece.
I do have better experience with headphones in general though, for obvious reasons. Oh, to have the hearing of my youth back again.

I was just listening to a 1972 Decca recording of Radu Lupu playing Beethoven’s famous C sharp minor sonata while reading this Good equals Loud string, and decided to check the SPL levels.  The first few notes of the first movement were in the upper 50’s decibel range with a low reading of 57 db, and much of the third movement was in the mid to upper 90’s db range with a peak of 98 db.  In my room that was a fairly loud third movement, but not as loud as the actual performance would have been sitting 8 to 10 feet in front of a big Steinway.  

Fairly often I listen at actual concert levels because it’s exhilarating and transports me to a live event. Concert grand pianos, full size modern orchestras, brass bands, string quartets, electric blues bands, tenor and soprano soloists, etc. etc. etc., are all very loud, and that’s the way I like to listen.  Call me crazy, and probably def down the road, but listening at lifelike volume levels makes the musical experience far more enjoyable.  I’ve always thought of Loud as one of the many aspects of Good sound!

Doug, your description is a lot like mine might be.

I almost always go for a "real" sound. My litmus test. Can my system make it sound (almost) like there is music playing here?

I grew up as a headbanger, but my father had country music or bluegrass playing every Saturday night in our home. Live musicians in our living room, giving it Hell!

Even a near proximity, all acoustic bluegrass band can reach stunning dB levels in a closed environment. I loved it! Headbanging to Steppenwolf, Hendrix or Led Zeppelin aside! It was real live music in my own home! I loved it!

I have greatly increased my music appetite and I now enjoy all forms of music. Possible exception being much of the modern hip hop and rap. No appetite for that genre at all.

When I listen to some hot jazz, I often find my levels are too loud for some, but if I measured it would be in the 80db range for some peaks.

Classical, I often get well above those levels, looking for that concert experience. Sound pressure levels as you described are necessary to even come close to a live performance level.

Then there are times when I want to feel my pant legs flap around from the sound pressure listening to some good old pounding rock music. That is still inside me, even at my age, and it surfaces fiercely sometimes with leather on.

I don't have a formula or any sugestions for our original poster, but I want my music to fool me into thinking that it is as real as I can make it sound.
That takes way more doing than just being loud.