Any suggestions for humidity with Z2 Auto?

I thought I really liked my z2 auto at first, but now I'm having a lot of trouble with the humidity factor. I replaced the humidity exchanger (or whatever it's called), but I'm still waking up after a few hours with an uncomfortably dry mouth and throat. This doesn't happen nearly as badly at home with my Airset 10 w/humidifier. This is proving to be a real hindrance to sleep when I'm away. My CPAP frustration level is rising a lot... I could really use some ideas.