Thanks for your answer.
So I’ve tried to install pisound on the top of samplerbox.
pisound check works like expected but samplerbox don’t work with pisound 
I’ve got an error message “Invalid audio device #2” (#2 is the device number of pisound card).
The message comes from the Python script here. It probably means that Python sounddevice.OutputStream function can’t open pisound.
Because samplerbox is just a tool to play WAV samples, I’ve related the issue to the one described in this forum here.
But the work around proposed (update .asoundrc) don’t work.
Any idea to allow pisound to play WAV samples ?