This one?:
PodTrak P4
zoomcorp.com
It has 4 XLR inputs, and OBS HATES more than X channels per device, where X is the channel count that OBS itself is set to.
OBS's audio is a pile of bandaids on top of a stereotypical bedroom streamer, and one of the things that is still there, is an absolute insistence that each device is its entirety, one signal. So your 4 inputs MUST BE quadraphonic (4 full-range corners). That gets mixed down to stereo, or whatever OBS is set for, according to the rules of going from format X to format Y, and THEN you get to play with whatever mess that creates.
If you had 6 input channels, and OBS were set to stereo, it would take the front two and copy them to left/right, and the same for the back two at a lower level, the center channel would go to both, and the subwoofer would disappear. Then it gives you that stereo signal to put filters on and otherwise play with. If those 6 channels were actually 6 different people each on their own mic, you can see how that would be a mess!
If you're doing anything beyond the stereotypical bedroom gamer/streamer, which might have a mono mic as one device and a surround-sound game as the other, then you need to do your audio work *outside* of OBS, like in a physical console or a DAW, and then bring the final soundtrack into OBS as its only audio source at all, to pass through unchanged.
DAW = Digital Audio Workstation. It's a complete sound studio, all in one app. It's designed *only* for sound, and it does that REALLY WELL!!! One of the basic, duh-obvious features in there, is to choose a specific channel of a specific device, not just the entire device. OBS can't do that.
Lots of different DAW's to choose from, with varying price and features, and not much correlation between the two anymore. I like this one:
