IMHO the manual is fully clear. Page 88:
Copy Mode (Playback Output Routing for iOS)
A stereo playback of iPad/iPhone defaults to output channels 1/2. To hear the audio also at the Phones output, or even at the SPDIF/ADAT output, the Babyface includes an optional Copy mode, where the playback signal of channels 1/2 is copied to outputs 3/4 and channels 1/2 of SPDIF/ADAT.
Use OUT to select OUTPUT Ch 1/2. Push SET. The current state of the Copy mode is shown by the three OUTPUT state LEDs:
Only Ch 1/2 lit: Copy Mode not active
Ch 1/2, Phones and Opt lit: Copy mode active.
Use SELECT to turn Copy mode on and off.
!!!Copy mode is not available when TotalMix FX for iPad is detected by the Babyface Pro!!!
And that app would have solved the problem (and will solve many more upcoming), so get it!