send I2C command to DAC IC through GPIO


I’m totally new for volumio, and sorry English is not my first language.
Currently I’ve tried both Pi3 and tinker board, I use a USB DAC connected to them, and installed volspotconnect2 plugin.
I can play spotify connect from my iPhone, I use wireless connection on the device, and everything works great! Thanks for the great work.

I have read some discuss on the internet, they said because Ethernet and USB ports on the board share the same USB Hub, so usually a I2S DAC is recommended.
So I would like to try to “connect” I2S signal from my USB DAC, which means by-pass the USB receiver.
My USB DAC is using CMedia USB receiver, CMedia FW use I2C to control DAC Chip, for volume tuning and other setting.
If I want to by-pass CMedia, I have to do what he does from volumio. Which means I not only open I2S connection to the DAC chip, but also I2C signal.
My qhestion is, how can I send I2C command through volumio through GPIO on the board? Is it possible to achieve that?
If any sample code or plugin will be even better.

Any suggestion is welcome, Thanks a lot!