Setting the bias on a conrad-johnson tube amplifier takes a screwdriver and a small red light. Each output tube has an LED beside it, and the owner turns a trim screw until the light just goes out. Bias is the resting current through each tube, and it drifts as the tubes age. Older amplifiers needed test equipment to set it, so c-j built the lights into its MV75 amplifier of 1979 and has put them in every tube amp since. The circuits follow the same plain thinking. Lew Johnson has long said that "simple circuits well-executed are the best approach," and c-j designs keep the number of circuit stages low. Jeff Dorgay of TONE hears "a slight bit of extra tonal body," and Steve Harris of Hi-Fi News calls the hallmark c-j sound "unobtrusively natural." c-j suits listeners who want tube tone and a deep soundstage without fuss.

The way in is the Classic Sixty Two, a 60-watt stereo amp that c-j calls entry level. Rob Johnson of TONE, who had never owned a tube amp, wrote that he "may now be a convert." It needs about 30 minutes to warm up, so he makes it the first stop of the morning. The Classic 120SE is the step up, with twice the output tubes and more power. Plan on a long break-in, since Rick LaFaver of Enjoy the Music heard it keep opening up until about 250 to 300 hours. If you want a single box, the CAV-45 S2 puts a passive volume control in front of a 60-watt amplifier. Dorgay ran about ten pairs of speakers from it with no trouble, though he found it a little short of power for Magnepans. One tip for owners of the GAT preamp, from Alan Sircom of Hi-Fi+: reverse the speaker leads, because the GAT inverts absolute phase.

Bill Conrad and Lew Johnson met as economists at the Federal Reserve in Washington. Conrad had his PhD from MIT and Johnson his from the University of Washington, and Johnson describes their early rivalry as "audiophile drag racing." They wanted to know why their two tube systems sounded so different and whether one design could combine the virtues of both. They studied the Marantz 7 and Dynaco circuits and spent more than a year on a preamplifier, without leaving their day jobs. The Conrad-Johnson Preamp, later named the PV1, came out in 1977, and Harry Pearson of The Absolute Sound gave it a Class I recommendation. Sircom counts Audio Research and conrad-johnson as the two main brands pushing tubes in the late 1970s, when nearly everything else was solid-state. The Absolute Sound inducted the two founders into its High-End Audio Hall of Fame in 2020, and c-j still builds every component by hand in Fairfax, Virginia.