Android still doesn’t handle USB audio very well. USB DAC dongles have their own volume settings, however Android doesn’t ever change this. This means that if a dongle has a preset volume level that is relatively low, android can never go above this.
Someone on Reddit has written a better explanation: https://www.reddit.com/r/headphones/comments/11wfe05/android_dongle_volume_issue_lets_ask_for_a_fix/
Help us get this issue higher up on android’s priority list by pressing the +1 button. I know it probably doesn’t affect many users here but thank you anyway!
Some dongles default their volume to 100% (or close to). Android doesn’t touch the hardware volume and simply controls the volume of the digital sound it’s sending to the DAC I believe.