Yesterday I measured the required current for the ADALM2000, rev. C. Only USB, no external power supply connected.
Software: SCOPY, no external devices connected.
Standby (not "Connected") 0,23A
"Connected" 0,41A
Signal-Generator 0,55A +- 0,02A
Network-Analyser 0,53A
all other modes 0,43A +- 0,02A
If you use the ADALM2000 only for measuring, no external power supply seems to be necessary.
Wolfgang