USB OTG Extension Cable and DAC I am trying to get audio through my USB DAC on various tablets with OTG functionality and I don't know why it's not working!

First off. It works just find when I use the OTG adapter straight to the tablet, however, I want to power the devices separately to reduce the power draw on the tablet so I have instead created a Y cable which externally powers my DAC. The DAC has power, however, the tablet will not send power through the DAC in this configuration.

The cable itself is working great. I have tested it using my phone and the DAQ works perfectly on it, however, on 6 different tablets now I have had NO LUCK!

Any ideas as to why the tablets are not sending the audio over USB DAC when the USB DAC is externally powered? 

The Cable has the red AND black wires snipped so there is no power coming from the tablet. I am wondering if the tablets need the black wire to be connected for some reason? My phone is USB-C while the tablets are all Micro USB.

Any help or thoughts are appreciated!
Solved! 

I went home and soldered a piece of wire between the two cut negative wires and now the extension cable works! I assume it has something to do with grounding out the ID wire in the micro usb. In anycase, SOLVED! Yay!

So as summary, I have an extension cable which allows my devices to get external power while still receiving signal from the tablet. The reason for this is to minimize power draw on the tablet and to extend battery life.