HeadRoom Micro Amp and Micro DAC
 

The Micro Amp is what you'd think it'd be; a headphone amplifier, suitable for use with various sources. It's got a couple of 1/8th inch stereo sockets (one for input, one for output), a volume knob, a three-position gain switch so you can use the volume control properly whether you've got the amp plugged into a weedy-portable, regular-line-level or pro-line-level source, a power LED, a power selector switch (of which more in a moment) and a crossfeed switch.



http://dansdata.com/microstack.htm