Is listening daily at an average of 85db safe?

It makes no difference whether it is music or a finely-tuned machine, like a HD...a dB is a dB.

It does. A machine at 85 db will output continuous noise at that level affecting the ear in exactly the same frequencies for a continuous period - like a jack hammer on the hearing it is specifically working certain nerve bundles and hairs.

Music (especially classical) will have much more dynamic range - so you get a lot of soft passages mixed with louder ones that may reach 85 db only on the louder passages.

The key with hearing is exposure. Giving your ears a break is very important. That break can be either several soft classical passages or an album of laid back acoustic music played in the middle of a session or harder and louder rock.

Variety is important - 4 hours of continuous Metallica played loud is much worse than an eclectic mix with some balads thrown in.

Does your system provide a non-fatiguing listening experience? Do your ears ring afterward in a quiet/noiseless place? How far from the speakers is your listening position?

I'll go out on a limb and say that if your system is not very resolving and causes fatigue after less than an hour into the listening session, and you continue to listen - then yes this level is not good for your hearing (it's probably not good for your hearing even if a system is non-fatiguing - 'causing one to listen longer - but at least it's perceptively enjoyable).

6 1/2 feet from the speakers, non-fatiguing, room is fully treated. I can't tell you if my ears ring or not because I already have slight tinnitus from many loud concerts without earplugs. (finally wised up and got some though)

I think it depends on the peaks, not the mean. I have read several articles on how to set up PA sound systems so the music is very loud but no one gets hearing damage. Read. Many things have been written in audiophyle mags on how the brain hears the average spl, but the ears hear the the peaks but tehy do not relay this info to the brain, so you can get fooled by music that is very uncompressed and has a high peak to mean ratio. Most pop/rock recordings are so compressed you won't have problem. I do have some home recorded rock music that is not compressed, and it will leave your ears ringing, even at levels that don't seem to loud.

Nemesis,

What matters is the peaks that make up the average level. I suspect the levels you use are OK. I assume you know dB(C) is spectrally pretty flat, whereas dB(A) reflects auditory sensitivity.

I don't understand what 6550c may have read. Acoustic energy impinges on the eardrum, is passed through the middle ear mechanism to the inner ear where displacement along the basilar membrane cause neurons to fire, such firing runs up the auditory nerve, and is represented in the auditory cortex. This, of course, is a simplistic characterization of the process. IIRC, at lower levels than the auditory cortex nerve activity between the two ears is compared for timing information. The hair cells along the basilar membrane can be damaged by excessive noise exposure, and various substances.

db