I received my T600 last week and have been playing around with it to test its capabilities and see if it will take its rightful place as my next phone (which I'm still not sure of yet).

I seem to be having a problem when a headset is plugged into the T600. When the volume is 2/3 to full max, I can hear a loud echo of my spoken voice into the ear speaker! It's extremely annoying and happens with 3 different headsets (including the one supplied by Handspring). It happens when I've placed a call and during a phone conversation (when the mic port seems to accept voice it is echo'ed back).

Is anybody else experiencing this problem?