USB

I plugged my phone (S8) running Android 8.0.0 into the USB of my Benchmark DAC 1.

I used a USB-C > A cable connected with a USB A-A adapter to a USB A > B cable.

It didn't work.
Using a Samsung supplied adapter (USB C to A) and an A to B cable, it worked.

 

The Benchmark DAC 1 is a UAC1 device.
This means the USB audio is limited to 24 bits / 96 kHz max.
Started Foobar mobile and without any adjustment or configuring the DAC started to play.

 

In Foobar I activated the re-sampler and set it to 96 kHz, the highest available rate.
Music kept on playing.
It look likes Android 8 support 24 bit / 96 kHz audio.

Host mode

Android 5.0 (API level 21) and above supports a subset of USB audio class 1 (UAC1) features:

Host mode is USB audio as we know it when connectiing the DAC to a PC.

The PC (or in this case the phone) is the host.

Powering the DAC might be a problem.

This can be solved by using a powered hub.

 

Old Android devices have a micro-USB connector that does not permit host operation, an on-the-go (OTG) cable is required.

OTG

USB Audio Tester

A little app by Daniel Sobe available on Google Play

 

Select the USB device, in this example my Benchmark DAC 1 USB

 

All the sample rates supported by the USB receiver of the DAC are listed.

 


References
  1. USB audio - Android Open Source Project
  2. PulseAudio vs. AudioFlinger - Arun Raghavan
  3. Making Fiio Q1 Mark II DAC working with Samsung Galaxy S8 - Head-fi 2018