I have the RAVPower 26800mAh Portable Charger with 30W Type-C Port battery, which has USB C to USB C, and turning on the MixPre6 does wake up and turn on the battery, I just tested it for I'll be using it tonight. I had the battery connected, and when I turned on the mixPre6 it immediately showed external power. For some batteries, it may depend on the sequence of plugging in the battery and turning on the deck. For sure pressing the button is a wise move always, and I am in that habit from some other deck and battery combinations.