just a shot into the dark …
how bout using the external outputs of the MD to mirror the main output / or using the headphone output to mirror the main out l+r … and use the aforementioned mirror out to monitor its levels (and assume they would be the same)
still you would need another machine to tell you if it is clipping or not, but assume the OT will only have 1 of its 2 stereo inputs in use, you could use that to monitor and the other to actually record …
good thread though, I have been wondering myself for quite a while … also, I d like to mention that the inputs on the A4 are only good until X volts / or ampere / or watts / or whatever the hell the unit is … (I posted this in another a4 thread) … afterwards the input is soooooo hot, that the PSU might get damaged