I have a Behringer UMC404HD interface that I cannot get output of if it using Alsa or Jack (Both Cadence and QjackCtl). The inputs work just fine through those though. And the output works just fine through Pulseaudio though, so I do not know what to do. I have to assume it stems from how the output is configured with alsa, but I cannot figure out how to do that. Any suggestions?
If the audio output is working in PulseAudio it should also work in ALSA and JACK. But ALSA would not be able to connect to an output device unless the PulseAudio connection to the device is stopped or suspended
The simplest way to disconnect the audio output from PulseAudio would be to go to PulseAudio Volume Control > Configuration tab ( pavucontrol --tab=5) and change the Profile for the USB device from Analog Stereo Output to Off
JACK should be able to use D-Bus to negotiate release of the audio output from PulseAudio
If JACK or D-Bus is not working correctly there should be warning or error messages in JACK logs about any issues
See QjackCtl > Messages window or Cadence > Tools > Logs window
If PulseAudio profile is set to Off to release the audio output, JACK should be able to connect to all the inputs and outputs