Hiawatha wrote:But why can't I mute those "instruments" that I want, send audio to mixer, mess it with kp effects, record it, and finally unmute everything from fruity loops and that's it.
Yes, you can do it that way. But what if you want to listen to the drums while tweaking another instrument? How are you going to play everything in time? Basically, if you can't listen to the rest of the track while recording, you will become frustrated very quickly!
The KA6 that Dave recommends should be fine too, although the Focusrites are also decent interfaces.