I have found a method to empty both, SONG A and SONG B.
It is a bit strange but it works perfectly.
First :
Create 2 registrations, I named them '_EMPTY SONG' A and '_EMPTY SONG B'.
'_EMPTY SONG A' is a registration with a MIDI file in SONG A (any), and nothing in SONG B.
'_EMPTY SONG B' is a registration with a MIDI file in SONG B (any), and nothing in SONG A.
Save these registartions somewhere you can find them back if you need them.
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1st problem solution:
Delete AUDIO file in SONG A
-> load Registration '_EMPTY SONG A' and the audio file in SONG A will be replaced by the MIDI file. If you also want to delete this MIDI file, go to MENU - MENU2 - SONG RECORDING - MIDI MULTI RECORDING - and then exit the screens by the cross in the right upper corner to the main screen and the MIDI file is also gone.
2nd problem solution:
Delete AUDIO file in SONG B.
-> load Registration '_EMPTY SONG B' and the audio file in SONG B will be replaced by the MIDI file. If you also want to delete this MIDI file, go to MENU - MENU2 - SONG RECORDING - MIDI MULTI RECORDING - and then exit the screens by the cross in the right upper corner to the main screen and the MIDI file is also gone.
3rd problem solution:
Remove AUDIO SONG A and AUDIO SONG B.
-> load Registration '_EMPTY SONG A' and the audio file in SONG A will be replaced by the MIDI file.
-> load Registration '_EMPTY SONG B' and the audio file in SONG B will be replaced by the MIDI file. Since SONG B is now being replaced by a MIDI file, the MIDI file in SONG A will automatically disappear.
If you also want to delete this MIDI file, go to MENU - MENU2 - SONG RECORDING - MIDI MULTI RECORDING - and then exit the screens by the cross in the right upper corner to the main screen and the MIDI file is also gone.
Hope my explanation is clear.
Best regards
Etienne