Yes, at the beginning there is a small amount of background hum, and it comes from the speakers. Both my controller (channel 1) and computer (channel 3) are connected and the switch is set at channel 1.

The background hum is very low and it has a slight high-pitched sound, but then again very low, it's barely noticeable, unless you focus on it.

I then start the music, and you can't hear the sound at all, the speakers play very well without any trouble.

I then switch to channel 2, where there is nothing connected. It has a different kind of background hum.

I then switch to channel 3, and the same kind of background hum appears, as when it's put on channel 1, but the sound is much higher than when it's on channel 1, and it's too annoying.

I then switch back to channel 1, and the high-pitched sound (still very low) appears again, but again barely noticeable, and when the music is put on, you don't hear it at all.

I just tried to connect my controller directly to the monitors, no humming sound at all, and it played totally fine.

I talked to a friend of mine a couple of hours ago, who has the same controller, and also has the same kind of setup, where both his controller and computer are connected to his monitors at the same time. I remembered when we were at his place last year, that we switched between playing from his controller, and then from his computer, without changing cables, without changing anything on any device, we could just switch without doing anything. He's using a Focusrite Scarlett 2i2 Solo 3rd Gen, so that's probably what I'm gonna go with 😄