The two audio interfaces you have are only 2-channel so typically you can only record a stereo mixdown of all your inputs.
However there is a simple way to record two (only two) instruments or mics to separate tracks in Cubasis.
- Pan one mixer input hard right and the other hard left, mute all other inputs.
- Create two audio tracks in Cubasis and configure (under routing) as mono input 1 and mono input 2
if you need more than two inputs, I’ve had much success with the Alesis IO Mix which records up to four channels (a dock which also charges the iPad) Other options include the Steinberg UR44 (6 channels) or FocusRite 18i8 (8 channels)
cheers,
642Carl