The (R-09) mic and line in's are both 1/8" stereo pairs, so there are indeed 'two' channels, not 'one'.
The (R-09) mic input does supply a ~3 volt DC mic power signal if you enable it. Not enough for some
mics, but sufficient for others. I think using any recorder thats powered by two double A cells
will drain faster if using it for phantom power. Perhaps you should look into a battery box/preamp.
I have the R-09 by the way. Me likey!
Greg