I've read countless threads where people describe they can hear "sibilance" in the mids or certain other non high-frequency bands, what are these people talking about?

Discuss.

Hello everyone!, I am thinking about getting a pair of closed / IEMs for portable use since my Grado's are pretty much useless on the street.   In your opinion, which pair offers the best sound for the money?, I favor detail extraction, snappy bass response and decent soundstage. I listen to...