I've added a iQaudio DAC-pro to my raspberry pi 4b running ubuntu 20.04. I cannot find the dac in amixer
$ sudo amixer
Simple mixer control 'Headphone',0 Capabilities: pvolume pvolume-joined pswitch pswitch-joined Playback channels: Mono Limits: Playback -10239 - 400 Mono: Playback -2000 [77%] [-20.00dB] [on]
I get very faint sound out of the pi's base headphone jack, nothing from the headphone jack of the hat card's jack.
How can I cause ubunto to recognize the iQaudio DAC-pro?