As long as we're getting historic I thought it might be fun to explore one of the most ground breaking audio products of all time, the McIntosh C8 Audio Compensator Preamplifier. 
Check that baby out! The McIntosh C8 Audio Compensator preamplifier was designed by Sidney Corderman—the chief engineer at McIntosh Laboratories—and came to market in 1955. It was an instant success. This was a preamplifier that had a number of advanced features for its time, including a motorized volume control and remote control (the first to have such a feature).
While the remote control was a cool feature, what really stands out in my mind was its Audio Compensator circuit which could correct for the frequency response of the playback system. (This was particularly important in the 1950s when HiFi systems were pretty limited in their playback responses).
This was, in my mind, the precursor to a full multiband graphic EQ plus easy-to-use bass and treble controls and a separate rumble filter. The McIntosh C8 was a roaring success and helped to establish McIntosh as one of the leading manufacturers of high-end audio equipment of its day. Pretty impressive.
