If you want to record in stereo on your Tascam Us122, just create a stereo track in cubase, and then put your left channel source through input 1(left of tascam) and your right channel source through input 2( right of tascam). Record enable your stereo track and you are away. It will record the two sources at once into a stero file. You can also record two mono tracks at once, eg vocals and guitar. You just need to tell cubase which one to go to which track on the screen and record enable both of them. On the mixer at the vey top it tells you the input source for each track which you can change. example In 1. Or In 1+2 for a stereo track.
Utsman