You are technically correct. From the OSHA website:
In 1981, OSHA implemented new requirements to protect all workers in general industry (e.g. the manufacturing and the service sectors) for employers to implement a Hearing Conservation Program where workers are exposed to a time weighted average noise level of 85 dBA or higher over an 8 hour work shift. Hearing Conservation Programs require employers to measure noise levels, provide free annual hearing exams and free hearing protection, provide training, and conduct evaluations of the adequacy of the hearing protectors in use unless changes to tools, equipment and schedules are made so that they are less noisy and worker exposure to noise is less than the 85 dBA.
I believe that 80 dB is a safer threshold for an average level and that our ears and brains adjust to this level and the enjoyment of the music is the same with zero risk. The dynamics are still preserved (depending on background levels). It is my new threshold.
this is further confused by the common A weighted standard for measurement whereas there are many other ways to measure and of particular concern is the volume at conversational frequencies (vs white noise) to which humans are more sensitive to long term damage. We measure each speaker at 85 dB ( a arbitrary holdover from analog days) per Dolby and THX reference but rarely with all speakers running.
I prefer to err on the side of caution. Thanks for joining the conversation.