@millercarbon
Maybe I am using the term revealing incorrectly. Maybe it's sibiliance in the high frequencies? I don't know, whatever it is it is uncomfortable to my ears at medium or high volume on certain tracks. A good example is the lead guitar on Wilco's Hate it Here. I don't ever remember this song as being bright. But don't get me wrong, this speaker is amazing in literally every other way.
Okay. So is it uncomfortable because its too loud? Or because it is harsh or grating? twoleftears is right about the massed strings. Violins produce a sound comprised of lots of little bursts produced as the bow is drawn across the strings. There's several strings on the violin and a whole bunch more on the bow and so then when you get a whole section of them playing together a lot of components can't keep the details straight and they all congeal together and that can be painful. When if they are kept straight its impressively moving. One might even say exhilarating.
Doesn't have to be massed strings. Could be soaring electric guitar, cymbals, anything loud and complex. The key is being able to keep all the many strands playing together separate.
Then when you get a better handle on what it is, are you even sure its the speakers? Often times people blame (or credit) the speakers just because it seems so obvious, when it turns out to be the speakers are just putting out the signal that came in.