USB headphones

quick question...

i play a lot of GM, and of course use headphones.
until recently, i used analog ones (with the jack you plug in).
worked perfect.
i could pinpoint ghosts and get a hs every time.

now i have USB headphones (logitech) and they won't correctly determine center.
this only happens on breath. all other sounds work fine, but i find a ghost, and he's dead center, the sound goes from left to right (full channel each time) and i can't pinpont.

it pans from side-to-side fine.

am i the only one having this issue?
am i doing something stoopid?