ALSA with 2 sound cards


I’m upgrading the sound in my car. I have a Raspberry 4B with USB SoundBlaster Play3. Now I want to put one more Play3 so I can have different output for the front and rear speakers. The idea is to apply a different ALSA Equalizer for each sound card. I’m with Manjaro ARM Linux with Xfce and the load is 6% when playing music.

How .asoundrc should look? What other software should I use to sync the clocks of the two devices. Should I try PipeWire or EasyEffects instead of pure ALSA?

Thank you in advance!