i use at the moment one gekko i have a simple power usb hub 1,5 A
its running on 200 mhz with a fan. diff set of 16.
its working fine for me.
using a power hub was for me really needed even on 50 mhz the miner direct in my laptop pc or raspberry was not working for me.
Im able to run a single 2Pac directly on a Pi 3b @ 50MHz. Other than the pook setting really high diff it's been working fine.
Ive been trying to find an appropriate powered hub, but may end up modding an existing powered hub with an external switching 5V psu.