Audiophilepure

https://www.stereophile.com/content/doshi-audio-evolution-stereo-power-amplifier

Doshi described the biasing process. “The front panel has four buttons around the display: Top left, power; top right, mute; bottom left, display on/off; bottom right, function. To activate the display, press the bottom left button. Now the display will stay on until the button is pressed again. Use the function button to step through the five functions: 1—hours elapsed, 2—bias for tube pair V1 (first LED below the window is lit), 3—bias for tube pair V2 (second LED under the window is lit), and so on until the V4 bias. Pressing the button for the sixth time will bring it back to elapsed hours and no LEDs lit up.”The bias settings for the amplifier can be adjusted for a slightly different sound to match system and personal taste. Typically, settings from 170 to 200 on the display are safe to use, with 180–185 being the norm. Lower settings will lean out the sound, and higher settings will fatten it up for a more ‘tubey’ presentation.”I biased the tubes near 200, which sounded best to my ears. The rest of the system was the J.Sikora Standard Max Supreme turntable, Allnic-H-5500 phono stage, Ampsandsound Yosemite preamplifier—which according to the manufacturer has a modest (for a tubed pre) output impedance in the 300–600 ohm range, depending on what tube is used in the last position—and DeVore Fidelity Super Nine loudspeakers.