Resonessence Labs HERUS Audio DAC and Headphone Amplifier - DSD and DXD HERUS is designed to operate with MS Windows, MAC OS and Linux. HERUS also has a very low 0.2 Ohms output impedance that prevents external noise sources coupling in HERUS is machined from a solid block of aluminum and is 63.5mm (2.5in) long, by 31.7mm (1.25in) wide The total distortion (THD) on any HERUS will always be better than 85dB (ie less than 0.005% distort HERUS will enumerate to the controlling computer and register itself as being able to handle volume