I'm a new owner of a DAAM that I've upgraded to Phoenix/HPR. I took it out for my first dive (safety test) in the pool. I was in a horizontal position and noticed that when my head was down (facing the bottom of the pool) it was noticeably harder to breath than if I lifted my head slightly (looking at the sides of the pool). I changed body position and was kneeling of the bottom and the reg was just on the verge of free flow...chin down = not flowing...chin up = just started to flow. I assume that is an issue with how I'm placing the tank and reg in my backpack. I also tried an inverted horizontal position that resulted in a complete free flow...no mystery there!
So my question is...Am I close to correct tuning or do I need to go back to school?