Hi gft !
Thanks for your fidelity
!You are right, there is a small delay between what you play and what you hear when using the "Microphone PassThrough" option. Technically it's because the iPhone doesn't offer a true "Direct Monitoring" option, like pro sound cards, so the input has to go through the app buffers to go out again.
This delay is compensated when writing to the track, so when it plays back on the second time, all is perfectly synced. But, unfortunately, it's impossible to get rid of the short delay on the "first time".
The solution you use (running two separate cables) is the best work-around !
Cheers
!Raphaël