Well, I'll chime in as a new user. I love "almost" everything about this 4x, but unless I'm missing something ... Korg took away a MAJOR tool that I'll miss: the ability to mix in an external audio signal AND still use the mic input. As far as I can tell, you have to choose the mic input or the line inputs, but can't use both at once. Seems weird, since they always had that option in the past. I'm not swearing to it yet, but it seems like the case. Anyone have a better answer?