Volume.

I don't put it at any one particular volume every time I listen. I start low and slowly put the volume up until the bass starts to get the amount of presence that I want. There should be a point where the music starts to focus and that's where I stop.

 

I listen more for spacial things rather than loud impact, but unfortunately, some people only want loud head banging impact from their headphone.

 

The volume that I end up with is reliant on what type and how it was recorded so it does vary. That's not to say that I sometimes just want it loud and fat!!!

 

So, in answer, it varies for me with which headphone I'm using, what genre I'm listening to and what mood I'm in.

It depends on the headphones as well as different headphones require different amounts of voltage/current for the correct listening volume.

I listen pretty loud if the gear is quality enough to not get obnoxious. HE-6 on speaker amps are so smooth and coherent, the volume just cries for more when things start groovin. But the portables never have enough to keep the volume at mid levels. I'm usually at 2-3 on the volume knob or over 80-90% on the PDP when I'm into a song. But that isn't a constant volume. Once I complete a loud song, the volume comes down again until that next "woah" song or passage comes along.

I had a couple of rude surprises when I had been listening loud and turned off my amp without turning down the volume. The next day I got blasted. Luckily my amp can be programmed to start up at the same volume each time.

The volume I listen at depends on the music. The only stuff I listen to very loud is certain orchestral classical music.

It's pretty hard to say without an SPL meter.  I mean, X / Y is a pretty meaningless measure unless it's known what level that corresponds to, the headphones used.  Estimating based on software level meter, DAC output level, amp gain, and headphones, I listen mostly around 55-75 dB SPL average volume, depending.  Actually, that could be pretty far off.

 

I have ReplayGain on and never bump the gain on the amp above 1x unless listening to certain classical music, sometimes.  At 1x gain and maxed out rotation (it's usually on 1x and lower than max), a 0 dBFS sine wave would be around 100 dB SPL, so it's always under that, at least.

In answer to the initial question, I have no idea how they do it. Or why. At CanJam 2010 a friend and I made it up Sunday and set up a bunch of equipment, including a FirstWatt F2 driving my Stax SR-007mkII. While I was away from the table a guy (my friend said "a kid") came up, put them on and cranked the volume. He said it sounded like being next to a pair of speakers. He told the guy to turn them down with a "those are really expensive, you'll ruin them" explaination. So now I get to live with probable holes in the diaphrams. My take? Max volume dudes are idiots. Ask them how they do it. Don't be surprised if the answer is pure Jeff Spicoli.
Edited by Clarkmc2 - 8/30/12 at 1:19pm

One time I was at the CES in Vegas. I dropped in the Sennheiser booth. All their phones are set up with max bass and max volume. I think that's the trend. Ever wonder if the guy drove by with the loud boom boom have any hearing left?

I usually have it on 11.

I specifically got a system that goes to 11.