USB DAC not detected (Topping E30 with Allo USBridge Signature Player)

Volumio Information

Volumio Version: 2.853
Hardware: Allo USBridge Signature Player
DAC: Topping E30

I just got Allo USBridge Signature Player running the latest version of Volumio. Connected my Topping E30 DAC to USBridge Player on the ‘Clean USB’ port.
While setting up the Volumio OS, the Output Device drop down menu only offers HDMI and Headphones. There’s no option to choose USB Device.
Topping E30 when connected to my iMac is instantly recognised by the macOS. So the DAC is working properly for sure.
I’ve checked all the connections and they’re fine. Reinstalled Volumio twice. Even tried with Moode OS. But the same issue. No USB device listed in the drop down for Output Device.
Spent entire afternoon trying to get Volumio recognise the DAC.

Please help me solve this problem.

Thank you!

UPDATE:

Connected the DAC to the front ‘WiFi/BT’ USB port. Volumio recognised the DAC and able to play music.

But when I connect the DAC to the rear ‘Clean USB’ port, it is not recognised by Volumio.

How do I get the DAC to get registered by Volumio when connected to the Clean USB out? (the way it’s supposed to be connected)

Please help!

Thanks.