An analog headphone amp you can use for your computer or portable player? Why not? Just plug this computer-friendly version of the Total AirHead into the USB port and let it run off the power bus, or switch BitHead on and its digital-to-analog converter (DAC) and power amp section will run off the internal batteries for ultra-clean performance and lower power drain on your computer. Plus it into your portable player, and it runs off four AAA batteries for about 30 to 35 hours.