|  | This custom 
        made vacuum tube head phone amplifier utilizes only 1 triode (6C45Pi super 
        tube) to drive SILK interstage line output transformer that has specific 
        output impedance to deliver the best drive to each high-end headphone. 
        Any output impedance to exactly match your head phone from 30 ohm to 600 
        ohm can be ordered specifically. The audio circuit 
        contains only 1 active component, that is 6C45Pi super tube, and just 
        three more passive components, one volume control, one bias resistor, 
        and one interstage line output transformer. we feel that this could be 
        the most simple circuit ever implemented. The most important element to 
        successfully implement this scheme is the quality of Interstage line output 
        transformer. In this case we dedicate to wind SILK I-541-H from best selecting 
        material and winding arrangement in order to achieve ultra-wide bandwidth 
        in term of frequency response (from 10Hz to 80,000Hz at -3.0dB) while 
        keeping the insertion loss to the minimum. The SILK interstage line output 
        transformer performance is so great that we do not have to apply any negative 
        feedback; therefore, this head phone amplifier will deliver unsurpass 
        listening pleasure and purity that contains unmeasurable distortion. While 
        prolong listening to head phone with disturbing IC circuit or transistor 
        with heavy feedback amp or tube circuit with capacitor coupling can cause 
        inevitable listening fatique, this effect is minimized with our design 
        of zero feedback, zero capacitor in line amp. |  |