Thank you for your help! In my original question, I was using a USB mic - but I later gave up and purchased a regular mic to plug into HD500.
You are correct that using POD audio interface as the mic wouldn't pick up what I'm listening. But I was able to hear everything through the headphone jack.
So I decided the make the headphone jack my output channel. But I also need to monitor the sound before going back into my PC.
So this was my final setup:
Guitar, Mic & PC output -> HD500 -> headphone output -> another audio interface (in my case, Zoom H1), adding monitoring headphone -> using Zoom H1 as the recording audio interface
And it worked. Though I wish I had something else other than Zoom H1 as an audio interface.