The AD-20 is a high quality battery operated microphone preamp coupled with a low noise 20 bit ADC. The SPDIF outputs are optical and coaxial and can drive standard consumer DAT machines or computers that accept digital audio I/O cards like the Zerfiro ZA-2. The main use for the AD-20 is location recording. Most low cost DAT machines have noisy front ends and a good preamp with a higher bit converter can improve the signal to noise by up to 15db.Features:Long battery life of 8 to 10 hours from one 9-volt battery.Low noise 125 db EIN unweighed at max gain (+45db).Dynamic range at minimum gain (+17db) is 97 db unweighedIndividual gain pots for left and right.Low battery indicator LEDExternal 9 volt input for studio work.Optional line input cables with 22db pads(10K input Z)Specifications:Power: 5.5v to 25v at 50 maSize: 3" x 5.75" x 1.25"Weight: Approximately 1 lbs.Input: Balanced 3 pin XLR at 10KOutput: SPDIF optical and coaxial