Note that althought the Yamaha has two inputs you can't really record them both at the same time as you have a mic input that pans to stereo and then a line level stero input as well that is mixed in before going to the pc. So really you either get a mic or a stero line in pair.
technically it actually has 3 inputs, stereo pair (or mono) AND a mic/line input, switchable according to what you're plugging in.
Experience over the last 2 weeks tells me you can record both the stereo pair and the mic/line input simultaneously.
We had the mixed drum kit mics into a stereo pair from Simon's rack mixer into input pair #1, and an ambient room mic in mic/line in #2.
Turned out the drum mics were picking up everything in the room as well (Trace Elliot 300W bass head, 1x15 and 4x10 cabs are really f**ing loud), so that track was not that much use, so I went back into the "studio" on my own, just me, the mics, mixer & laptop, and I recorded "clean" drum tracks for 5 of our 9 songs by playing back to the previously recorded version. Tricky for a drummer but if you can play to a click track, you can play to your own previously recorded versions. Took me about 2 hours. 3 more to do... (song 9 is an acoustic number, no, or very little, drums)
shame I hadn't bothered to tune my snare before hand, £300 snare drum may as well be a £30 snare drum if it's not tuned properly. ah well, 3 songs still to do
I think you can even add drums in ai but i never got the hang of using that interface well.
not a problem for me