Harmonic Distortion

The ADE-24.1 Analog Digital Enhancer is an accessory that has been around for a long time. It works at low voltage (e.g., RCA analog output from CD player, iPod, etc.) and manipulates the harmonics. I got one of these units at the California Audio Show and the demonstration definitely indicated that it could improve sound (make it sound more appealing, and widen the sound stage), so I decided to bench test it to see what it does.