Peak listening levels-

The answer will vary greatly depending on the kind of music that is being listened to, and also on how much dynamic compression has been used in the engineering of the particular recording.

I have a few classical symphonic recordings in my collection that have a dynamic range (the DIFFERENCE in volume between the loudest notes and the softest notes) of more than 50 db. On those recordings there are BRIEF dynamic peaks for which I've measured 105 db SPLs at my listening position.

With highly compressed rock music, on the other hand, that will often have a dynamic range of less than 10 db, peaks are generally in the 80s at my listening position.

Another key factor, btw, is how good the sonic quality of the recording is (apart from how dynamically compressed it may be). Recordings having better sound quality will tend to be listened to at higher volumes than recordings of similar music that have poorer sound quality.

Regards,
-- Al

Al's comment on dynamic range vs. listening levels is spot on. The wider the dynamic range the higher the level I'm listening at. Primarily because otherwise you just can't hear the content at the very lowest level.

Just so you know, there are those of us, reckless seekers after supersaturated cosmisonic orgasms in the rarefied realm of the Grand Overwhelm, who dare to challenge fate by listening to our stereos blasting out at peaks which often frighten the Radio Shack device into readings of 107-108 db, at the listening chair. These moments occur in my room only on recordings with overpowering bass drums and/or organ pedals, but they exhilarate on a physical and I dare say emotional level that is not for the cardiac-challenged.
This kind of listening (I am speaking now of symphony orchestras and symphonic bands) can only be enjoyed if the rest of the recording involved is superior throughout the audio range, smooth and of very low distortion.
Also, obviously, one needs a speaker capable of accomplishing the exceptional and an appropriate amp to drive it to attempt murder. Otherwise, at such macho levels of gain, the unpleasantness that must always come as the dark cloud on the silver lining of Audio of even the highest quality, will be intolerably present and offensive enough to prevent any impulsive upward twisting of the volume.
I also recommend, for true aural thrill-seekers, a trip to your local orchestra and place to booty in the front row or two at the very feet of the glorious string players. Often, even usually, the box office prices the explosive first few rows below other seats. For those who, like Siegfried, fear nothing, go there and seek ye the splendor of a big Mahler symphony or a Respighian extravaganza and learn why nothing will likely ever sound quite like the real thing.