Manual switch to initialise USB driver

[Catweasle]

Trying to stop Android charging Fiio USB DAC

First thanks USB Audio player Pro got the DAC working with Andriod, now I am trying to stop Android from trying to charge the DAC which has it’s own battery.
Without root, where the may be a possible proc setting that could be switched I can see a couple of options:

• Your driver has a switch ( which may not be possibly without root )
  
  
• Chop the power line in the OTG cable
  

Given I had two OTG USBc to micro cables I chopped the power line in the OTB cable. The result is Android still recognises a USB cable connected, but Audio Player Pro does not initialise the USB audio driver. DAC not working but also not being charged :-)

I wonder if a manual switch to initialise your USB audio would work?

tnx