Can a multi-output device have an input? I am setting up to live stream music. I've installed a virtual sound card (Blackhole) and created an aggregate device consisting of my mic input and the virtual output. I then set OBS to use the virtual device as the audio source, and switched on monitoring. It works! I can hear the music and my voice. The problem is that OBS is creating latency on the monitoring, so my voice is out of sync.

So, can I create an aggregate/multi device which has one input, and two outputs? That way I can have the input for the mic, output directly to my sound card so I can monitor, and have the virtual output going to OBS for the live stream. Is this possible? I can't find a way to add an input to a multi-output device, or to add more than one output to an aggregate device.
Ah, I actually found a workaround. My music software (Reason) allows you to wire up the audio output to any channel on the device. Because I created an aggregate with the input and the two outputs, I could split the audio and wire it to the output channels for both the real sound card (for monitoring) and the virtual one (for capture by OBS). It works, and there's no latency.