Why does everything work with regards to recording on the laptop, but not the tower computer? In both cases, system sounds, including videos, sound files, YouTube, etc. are unaffected on either computer please consult the pictures of the Studio Controls settings.
Lenovo Legion 5i i7 laptop with Fedora 33 Cinnamon spin and Fedora Jam installed.
Artlink i9 tower computer with Fedora 33 Cinnamon spin and Fedora Jam installed.
The laptop has a Behringer U-PHORIA UMC202HD USB card connected.
The tower computer has a Behringer U-PHORIA UMC204HD USB card connected.
On the laptop, it is possible to get input sounds through the USB sound card, both voice and bass.
On the tower computer there are no sounds (voice or bass) that go through the sound card and can be recorded. The level meters (green and red lights) do register sound on the USB card, however.
To keep this simple, I have used gnome-sound-recorder for recording. I am using the Jam Studio Controls settings to control all sound on my systems. Both appear to have the same settings. The jack server was not active when I tried to record.
I notice the two Behringer devices are slightly different models? Does the model plugged into the tower work as expected on the laptop? This will at least help you narrow down whether it is a issue specific to said USB device, or configuration of host.
Unfortunately, it is more complicated than that. I think that you are on the correct track however. Below is a picture of the UMC204HD. It has both left / right “playback outputs” and “main out”. Currently, it is connected to the playback outputs 1 & 2 (left / right), as the RCA jacks are compatible with my Samson monitors. The UMC202HD sound card only has 1/4" jacks, same as the “main out”. For the UMC202HD, I am using a 2 x 1/4" to mini jack cable, as it is connected to regular computer speakers.
When I connected the UMC204HD to my laptop (and external computer speakers, using the 2 x 1/4" to mini jack cable), I could record my bass with the gnome-sound-recorder program. So it seems that maybe I need 1/4" to RCA cables (if they at all exist).
I still think that there is something odd, though. As the output connections, regardless of whether connected the one place or the other on the sound card, are outputs that go directly to speakers - not to the computer. I don’t see how they could affect my ability to record, but still have functioning, normal system audio?
Some audio systems are designed to physically prevent feedback so internal switches on the jacks prevent input & output at the same time. This might be a factor there.
I also wonder if the +48v switch has anything to do with that? Are those settings the same on both devices?
Yes, they are the same on both sound cards.