The A&H has an external 12V 5Amp DC PSU
It seems to go off when unattended rather than in use, although there were a few crackles at the venue last night, which worried me, but our guitarist thought it might have been a loose lead. I managed to take a quick clip of it crackling yesterday (rushed downstairs to get the last few seconds if it), and you can just make out that there are spikes on all the channels when this is occurring.
A&H CQ18T crackling.mp4