I'm sure you can use a microphone with it but the quality of what comes out depends on what the microphone picks up?
If it's human voice a suspect a bad result. If it's an acoustic guitar, it will probably work well.
The harmonizer will detect the frequency of the incoming signal and generate harmonies. A human voice will normally result in a signal composited of a whole range of frequencies. The HR-2 will probably have difficulties picking up the correct frequency to harmonise over.
I'm not sure if the tracking would be very acurate with a microphone. If you were using it in the studio to process vocals, I'm sure it would track a bit getter. Maybe if you are first running your live vocals through a compressor/limiter it may improve the tracking, but that's just a guess. I would try it out using my HR2, but I don't have a mic at home to try it with.
i just tried it, wow. it sux! i even ran the signal into the detector in as well. everything sounded like s***.
i used an sm 58.
the detector in is a jewel. it really helps the signal stay on track and responsive.you can just use the input if its first in the signal chain. if its down the line youll need the splitter for the detector.