OK, so it's super late in the thread, but I only recently learned from one video how to do it, and it's so bizarre, that the chances of people replicating it are slim. And the video doesn't explicitly mention microphone which doesn't help. So, for posterity.
While the OP was not explicitly asking about HW monitoring, still this is the closest thread, so here it'll go.
There IS a way with Helix to simultaneously process, HW-monitor and record the processed guitar AND processed microphone signals on separate(!) USB outputs. This is in addition to the well documented way of recording dry guitar and mic on USB7/8. The comments above addressed either the separate channels for processed signal recording (losing HW monitoring in the process) or dry signal recording. But that's suboptimal.
First of all, basically all of the credit for the discovery of this method goes to Scott Uhl, the author of this video:
I just slightly adapted his findings for the microphone use case.
In order to achieve the monitoring and separate recording of guitar and mic, you need to split the mic path, like Scott is showing in the video. But instead of splitting the input part, just do the output one. Then, on the first path - send the processed mic to whatever you're using for monitoring. 1/4, XLR, Digital. Anything BUT the default "Multi" output. This is because the default Multi also sends to USB 1/2, which we don't want.
The second mic path send to whatever output you prefer to record just the mic on. I.e. USB 3/4.
Now you're hardware-monitoring a mix of the mic and the guitar on your default output, say XLR, recording your processed guitar on the default USB 1/2, and recording the processed mic on USB 3/4. In addition, as always, you can record the dry mic and try guitar on USB 7/8.
Note: In order for the extra paths to not collapse you need to have a block on them. Any block will do and the block can even be bypassed.
I can't believe this functionality is fully supported by Helix hardware and software, yet the UX of configuring it is so abysmal.
