This app can record up to 8 tracks.
Then mix recorded tracks.

Features:
- Enable to change volume, pan, playback rate and pitch for each track
- Enable to import downloaded music from Music App
- Mixed audio can play and share from Library menu
- Volume range: 0 ~ 100%
- Pan range: -1.0 ~ 1.0
- Playback rate range: x0.5 ~ x3.0
- Pitch rate range: -2 oct ~ 2 oct (Changed by semitone)
- Metronome
- Import an audio file from other apps by share action
(Supported files: wav, mp3, mp4, m4a, aifc, aiff, aac, caf)

iOS 11 is recommended!!
For iOS 11, changed volume, pan, speed and pitch for each track is preserved when mixing.

If you have requests for more features or suggestions to make improvements, just write a review.
I will do my best!