There is an attachment that can be used instead of the mic ones that would allow 6 Combined XLR/TRS inputs. The 2 this adds do not have phantom power.

You can get 6 independent inputs with this. Also, tracks can be independent or stereo pairs. You change this by briefly clicking a pair of buttons (eg. 3 and 4) together. This also works with the "XLR attachment" but the mic attachments are fixed as a stereo pair.