When configuring jack with patchbox command line tools, it seems that -S and -s option are activated.
According to doc
-S, --shorts
Try to configure card for 16-bit samples first, only trying 32-bits if unsuccessful. Default is to prefer 32-bit samples.
-s, --softmode
Ignore xruns reported by the ALSA driver. This makes JACK less likely to disconnect unresponsive ports when running without –realtime.
Is my 24 bits PiSound Card downgraded to 16 bits as a defaut behaviour ?