Setup: NAD VISO HP50 on iPhone 4S playing 320kbps files, converted from lossless FLAC.
Lately, for some reason, in the majority of songs in my collection, the s and t sounds are very sharp and hurt my ears. This really only applies to the voices since cymbals and violins all sound great to me. It's gone to the point where I now mostly listen to soundtracks and other instrumentals to avoid those sounds. Can anyone explain what's happening?