Finally pulled all the pieces together for my MixPre-6 external power source. I know the Anker PowerCore+ external solution would have been easier and less expensive but I am not sold on the durability of the USB-C port for field use. This solution also leaves streaming from the USB-C port as an option in the future. When I made the decision to go this route, I contacted Hawk-Woods and had them make me a custom Sony dummy with a 2.5mm right angle plug instead of the hirose, this saved me the extra coin on a hirose to external adapter. I am not sure how the MP-LMount pulls power from the dual batteries but I am hoping the RAV will act as the primary so I can hot swap the external with the NPF as the backup.
Testing setup: Firmware 1.11, Custom Mode w/ Basic Gain, Brightness 1 & 1, Monitor gain at 40, 2 channel phantom, and recording ISOs and L/R Mixes, Bluetooth on
Source: MK41s > KCY 250/5 > JT inters > +60V PFA > MP6
RAVPower 23000 only - 14 hours
Sony NP-F570 - 1.5 hours
I will add more run times as I perform 4-channel and line-in tests.