Just got done with an all-night mix down session (tight deadline). I had to take breaks because my ears were getting tired. I was losing my ability to discern subtle tones. If I didn't take a break, I knew I would wind up with a product I didn't like. I find that after about 2 hours, my ears need to take a break. How long does it take for the ears to get tired? Anyone have any tips to ease ear fatigue?