Audio tracks!
Audio tracks!
Audio tracks! 
Basically an exact copy of the implementation of audio tracks in the big sequencers (Logic, Cakewalk, etc):
Each audio track has an assignable audio input and can be armed.
If multiple tracks are armed then Renoise should record multiple inputs simultaneously.
A really nice bonus would be a “recording stop criterion”:
- threshold (if input signal falls below X db)
- user keypress
That way you could, while recording, stop the midi playback at the end of a pattern and still record the audio tails.
Otherwise you would have to add an empty pattern to make sure no new midi notes are send during the audio tail recording (that’s my current way of working).
I made a post a while back in the Audio Tracks brainstorming topic about this:
It would be a fantastic addition to Renoise
Cheers,
Xeryc