Thanks Alex,
Could I instead do the following:
1. Connect instrument-A to line-input-1 and apply eq, compression, fx etc.
2. Record line-input-1 to Qu-Drive track-1.
3. Disconnect instrument-A from line-input-1.
4. Patch playback of track-1 from Qu-Drive to channel-1.
5. Connect instrument-B to line-input-2 and record it to Qu-Drive track-2.
6. Re-connect instrument-A to line-input-1.
7. Assume original channel-1 settings (compression, fx etc) that were used when the instrument was originally recorded to the Qu-drive.
8. Alter channel-1 settings (e.g. compression).
9. Re-record line-input-1 to Qu-Drive track-1 (overriding original recording).
Thanks again.