I recently received a DAC+ ADC Pro and a AAmp60. I have hooked them to a rpi4 with rasping lite + minimal desktop. I have sound from the dac through external amplifier, but no sound from the AAmp through my speakers. I have plugged in the 6 pin header and I am powering everything with 19V from a battery capable of delivering 3.5 amps. The speakers are 4ohm and are capable of 200w peak rms, and as such may be a bit demanding, but I believe it should work.
Are there any esoteric subtleties that I have overlooked?