Head Box DS is a high-end headphone amplifier with a USB input and built-in D/A converter. Having this feature set provides the ability for direct connection of digital sources to the Head Box DS for headphone listening. Additionally, an analog output allows the unit to function as a D/A converter for the same input sources when connected directly to a preamplifier. The USB input is a 24-bit/96kHz asynchronous design delivering superb sound quality from a computer audio source. Additional digital inputs include a coaxial RCA and Toslink optical that can be used to connect to, for example, a digital output of a CD Player. The dual mono amplifier topology employed uses very high quality component parts including ultra low-noise ICs and high-reliable relay switches. All controls are located on the front panel for ease of use and the Head Box DS features a large and legible LCD readout. An outboard power supply is included and in 2013 an optional rechargeable DC supply will be made available.