Dry mouth problem with different machine

I have been using a Remstar M with the heated humidifier for a couple of years with a ResMed Ultra Mirage Full face mask
and am bothered most of the times with a dry mouth. Recently I started playing with a DevilBiss Auto adjust LT model
8054 without a humidifier. Some how the 8054 doesn't dry my mouth out I wonder why? The remstar is set at 14cm
and the 8054 is set 13cm to 15cm. I have a feeling the 8054 lowers pressure on exhale but am not positive about this.

I sure would like to have the manual for the 8054 but can't find it on line and no the 9000 manual would be of no
help the 8054 only has 2 switches no fancy arrow buttons.

Are you opening your mouth at all? That can cause dry mouth.