@ewp thanks, I am specifically interested in the internal DAC, this is the reason for my inquiry. I will try jack, but it appears to just use ALSA under the hood.
this thread documents how the ETH peripheral is confusingly interacting with the Audio Out pin. My experience matches this description, where I hear periodic pops (bursts of high-speed data), so I believe there is some configuration that needs to be modified, but I am unable to determine quite what, based on the thread 【i2s】Milk-V Duo添加speaker——max98357a解码器驱动 - #58 by LangZhao