I have AMT2050 v1.2, amplifier which I added RCA input and turn on-off switch, along with banana plugs for the speakers. It has potentiometer already installed.
I am getting hum, when I turn the volume past half-way only with AC source input. With my CD player and PC, it has the hum. When I play my iphone and nano mp3 player, both are battery operated, the background is totally silent with the voume turned up high and sound is excellent. When I tried to change my DC adapter (32V, 3Amp) from 3 prong to 2 prong (US), I still get the hum. Any suggestions will be appreciated.