Recording video and audio with external input to computer with Canon 600D I like to do drum covers, but the process always takes ages. I have to record my sounds from my electronic drumset (TD-9KX) to Cubase via a Tascam US122-MKii interface. Video is captured with a Canon 600D. Afterwards I have to export the audio from Cubase and insert it in Adobe Premiere together with the video and make sure both are in sync. That takes a loooooooong while!

Because the 600D has an "external mic" input that supports stereo, I thought it might be very well possible to record from my external drumset, to the interface and via its output to the 600D to the PC. This would mean that everything is in sync. Is this correct?
It should be.  You might end up with impedance mismatches that have to be dealt with, so it might take a few other (relatively cheap) steps to get there (devices called pads, which bring down the level), but it should work.  The quality might not be quite as good though.