Thats not accurate
The AMBrc decoder WILL run off your laptop/desktop USB port with no other power supply needed!
The latest AMBrc3 decoder WILL NOT operate off the USB cable. (It dosen't have this option)
The AMBrc, rc3, and the charging rack ALL operate on 12dc when the power supply is used. This gives you a few options
I have run my "rc" (when I had it) and now my "rc3" off a 12vdc solar system. I run the laptop and decoder off 12vdc, and the printer and PA system off 120vac inverter power.