Hi Tomasz, Karol, Ranjani, I wonder if you have any clues on why $subject happens. We have a simple pipeline like this: PCM0 --> B0--+ |--mixer-->B1-->DAI PCM1 --> B1--+ Subdevices are created like this: oot@imx8qxpc0mek:~# aplay -l **** List of PLAYBACK Hardware Devices **** card 0: sofwm8960audio [sof-wm8960-audio], device 0: Port0 (*) [] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: sofwm8960audio [sof-wm8960-audio], device 1: Passthrough Playback 1 (*) [] Subdevices: 1/1 Subdevice #0: subdevice #0 But, when we use aplay in the following order: $ (1) aplay -Dhw:0,1 -f S32_LE -c 2 -r 48000 file1.wav $ (2) aplay -Dhw:0,0 -f S32_LE -c 2 -r 48000 file0.wav everything is OK, mixing works. But when the order is reversed: $ (2) aplay -Dhw:0,0 -f S32_LE -c 2 -r 48000 file0.wav $ (1) aplay -Dhw:0,1 -f S32_LE -c 2 -r 48000 file1.wav (1) aplay exists with an error: aplay: pcm_write:2057: write error: Input/output error I wonder if you met this. Topology looks to be symmetric with respect to PCM0/PCM1.