The Doge 6210 has features that you would expect in s a state-of-the-art headphone amplifier. Two EL84 tubes and two 12AX7 tubes make up the gain stage. A switch lets you chose between “Normal” and “Music Hall “ sounds. The unit comes with two headphone jacks. Chose headphones with 60, 300 and 600 ohms. There is also a “line out” that allows the unit to be used as a preamp.