Im running Windows 10. So what do I need that is similar to UR24C? I was told I didn't even need it because the h9000 is a DAC it inself and I could just plug it with USB on the PC and then plug the Magni 3 there on the h9000 or something
Yes, the H9000 is a DAC in itself and the analog performance is very good. However, it doesn't (yet) have gain control over the analog IO, so you would need to plug it into a mixer or something else with analog gain controls. We are going to add internal gain controls in a future update to make it more easy to use as an audio interface.
You could connect two of the analog outputs to the Magni 3 and two of them to your monitors via a monitor controller that would allow you to adjust the volume. Note that the H9000 outputs are balanced. You would need to make sure to get the right cables.