I owned a ZH-270 for the better part of a year. Very musical little amplifier, and very user-friendly. I had considered becoming a Berning dealer, but the little amp really wasn't up to driving the speakers I sell (Sound Lab electrostats). I was sorry to let it go. I especially liked the clarity and natural timbres in the midrange, and the variable output impedance which allowed optimizing for different types of loudspeakers. Superb with Original Quads. Amazingly lightweight and cool-running for what it does.
