I have a clone of the 8323. Whilst reading this thread I pulled out my Bingle "Denmark" B-850-M to give them a listen after a session with some very old punk rock on the JVC HA-S500 and these do not suck. Not much of a soundstage, instrument dimensionality isn't really there, instrument location is a fuzzy blob disc somewhere over there, but tone is warm and good and harmonically it's ok considering that I paid $24 for the pair. The 850-M compare favourably to the S500 and in fact share many similarities.
I usually listen to volume at 7am to 9am, but wanted to see how this scaled up so on
Shoot to Thrill by AC/DC I got them as high as 12 noon before my ears said 'enough'. The headphones could hand the volume, my ears could not.
I put my valve amp up up to 5pm, max volume, with the cans off my head sitting on the shelf. Clear and clean like a speaker. I never listen to anything above 10am when I have the cans on my head, so this was waaaay louder than I would ever listen.
So, yeah, these would be a great pair of cans to rock out to at maximum volumes.
Don't expect any finesse or subtlety, however.