Input from usb Digitone to Modep to Behringer Xenyx302 USB output

I am trying to get audio input coming from my digitone using usb, apply some effect to it with Modep and output to my usb behringer mixer. Outputing audio to the behringer mixer work pretty good, but the audio coming from digitone through USB is not really nice and very often glitchy.
To do this I configure Jackd (/etc/jackdrc) like this:

exec /usr/bin/jackd -t 2000 -R -P 95 -d alsa -d -Chw:Digitone -Phw:CODEC -r 48000 -p 1024 -n 2 -X seq -s -S

I am on rpi3. Is there anything to do to get better sound quality from the Digitone?

It’s a bit tricky using multiple sound cards with the same Jack server. You could try using some bridge client, instead of configuring Jack to use different cards directly, see:

(you could try the alsa_in client, you might have to hook up the audio connection from the client to MODEP yourself, using jack_lsp to list clients and jack_connect command to make the connections)

Actually it was how I was doing before. But at the end, I don’t need 2 differents inputs from 2 differents sound card. This is why doing like I did simplify thing a lot.

Also, if I only use my digitone as sound card (alone), I also get glitchy sound. I wonder why it work well with my Behringer mixer, it also work well with my OPZ, but with digitone the sound is not good :-/

I just received my RPi 4, and there it work perfectly.
But now, there is another problem, after playing 2 minutes there is a kind of very loud bass sound starting… and 2 min later, it stop, very weird.