copied this from review on the amp
The Adcom's input impedance at 1kHz was 47k ohms, and its output impedance was uniformly low—ranging from 0.02 ohms from the bass to the upper midrange and increasing slightly to 0.03 ohms at 20kHz. The gain of the GFA-565 was 27.1dB into the unbalanced inputs. I found that the three gain settings on the balanced inputs—0dB, +4dB, and +6dB—actually gave quite different readings. The +4dB setting was actually 8dB down from the 0dB, the +6dB setting was down 14dB from the 0dB. Unweighted noise was 70dB below 1W into 8 ohms
Read more at http://www.stereophile.com/content/adcom-gfa-565-monoblock-power-amplifier-measurements#o0IIiIqQ6YtF...
The Adcom's input impedance at 1kHz was 47k ohms, and its output impedance was uniformly low—ranging from 0.02 ohms from the bass to the upper midrange and increasing slightly to 0.03 ohms at 20kHz. The gain of the GFA-565 was 27.1dB into the unbalanced inputs. I found that the three gain settings on the balanced inputs—0dB, +4dB, and +6dB—actually gave quite different readings. The +4dB setting was actually 8dB down from the 0dB, the +6dB setting was down 14dB from the 0dB. Unweighted noise was 70dB below 1W into 8 ohms
Read more at http://www.stereophile.com/content/adcom-gfa-565-monoblock-power-amplifier-measurements#o0IIiIqQ6YtF...