In addition...
Even the Anker power supply is not perfect.
I have now hooked up the PAW to a small speaker, and it was very noisy (with PAW noise). But there is no noise when I run the speaker on internal battery. (Same problem I had previously.)
Ok, I know now that I can stop this with a ground-isolator in the audio circuit, but it does mean that the Anker is far from perfect.
P.S. The vario also puts out a load of crackle and hiss, when connected to the speaker and the Anker together. But again, complete silence if the speaker runs on internal battery (or if I include the ground loop isolator).
R