Some video capture cards appear as two devices: a video input that may or may not be silent, and a separate sound card. You might need to add the sound separately from what ends up being the same physical device.
Also, cheap USB capture cards are often deceptive. USB 3 connector, and sold as such with all the relevant comparisons to USB 2......but it's actually a USB 2 chip inside, with all of the ramifications that go along with that. You can't shove uncompressed FHD through USB 2, for example, so it *must* compress, in the card, before it even gets to the computer and OBS.
To actually get what you think you're getting, go with name brand USB or internal, and expect to spend about $100 per channel.
