No sound on output when trying to perform live with Logic Pro X

I'm very new to Logic Pro X, please bear with me.

I just bought a new MacBook Pro (with M1 chipset), and my target is to perform live (not a recording):

1. Capture guitar and vocal through an Audient iD4 interface (2-channels) plugged to my Mac
2. Apply with Logic Pro X some effects on guitar channel and mic channel
3. Output the result from Logic Pro X to a loopback interface (I have installed Loopback from RogueAmoeba)
4. Capture the loopback output from Logic Pro X into OBS
5. Monitor the Logic Pro X output (post effect) with a headset plug on my audio interface

To handle 4. and 5. simultaneously, I have created with Audi MIDI Setup a Multiple-Output device, containing my audio interface iD4 and the loopback interface.

In Logic Pro X, in Preferences -> Audio -> Devices, I have:

• core audio: enabled
• output device: Multi-output iD4+loopback
• input device: iD4

And in Preferences -> Audio -> General:

• Software monitoring: disabled

in Logic Pro X, I have created 2 tracks (guitar and mic), using input 1 and input 2. The tracks are "Record enabled". When talking in the mic, the meter next to track 1 in the mixer windows is moving. So the sound seems to be routed properly from the iD4 interface to Logic Pro X. But I don't receive any sound in the monitoring headset plug on my iD4 interface, nor in the OBS through the loopback device.

If I enabled Software Monitoring in Preference -> Audio -> General, then I'm getting sound in OBS. But the manual of my audio interface is stating not to use Software Monitoring, because it is adding some latency.

There is probably something basic that I don't understand in Logic Pro, regarding the meaning of "audio output", "monitoring" and "channel". Is it because Logic Pro main purpose is to record to a file so "output" configuration mean "monitoring output" ? Any resources and advice to help me understand better this part and how to achieve my target are the most welcome!

Thanks,

Jean-Paul