oh yeah that jibes with your (Chuck) experiment with 2.45 aH NiMH's that lasted about 2.33 hours (2.45aH * 1.2V * 8 = 23.5 Watt-hours, you actually got about 10 watts of load.) It will vary depending on what mics you are using since different mics consume different amounts of power, and it will be longer if you're using line input.