Your question is really ... “how do I use my RME interface?”

We highly recommend: RME Website

The answer is the same...
Select your audio interface
Follow the instructions on how to operate that device (Driver, setup, etc.)
Connect all hardware synth and software synth outputs to the audio interface. (It is the audio interface’s job/function to handle inputs and outputs — both inputs to your computer and outputs to your sound system).

It is that simple and that complex. Your first hurdle is to connect the 1/4” Main L&R Outputs of the MONTAGE to your soundcard (audio interface). How are you accomplishing this? Do you also have the MADI/ADAT Converter? For a 72-channel, 5.1 Surround system you have not listed near enough gear for anyone to help you get connected!

no, it is ok, it does not matter witch interface . i have to plug the montage main outputs jacks in the rack converter and eventually the auxiliary output too for at least get more output for the surround mix.just that simple and render the midi later for get a digital quality. i suppose a better way will be to have a Mac. i think it would be the end of my "schizophrenic" attitude with the montage. it is just that i was confuse with the sound system that is connected with my sound card and i was asking myself how to monitor the digital sound of montage in this system i know, looks simple but it was not for me. With this set up i suppose that i lose the possibility to feed directly the 16 digit output of montage in the surround system. i have to say as excuse that my systeme is quite complex for me as i have to rely 3 sound cards. the RME HDSPE raydat on the pc and komplete 12, the montage and his own sound card and the iPad with his Steinberg UR 22 mkII. i let you immagine all cables running in my studio and before in my head, ah ah ah. i hate cables but wifi is not a solution for me ,. i try to avoid waves at home. thanks everybody.

You may think that getting Mac will solve all your problems... it will not. It will simply give you more things that will confuse you also.

With a Mac you will be able to record via both interfaces simultaneously to the computer. But you still must connect just one of them to your speaker system. This means in order to monitor *direct* while recording one of the audio interfaces will need to be connected to the other.

You’ll see... Monitoring direct may not be a huge thing for you, at this time, but it will come up when recording. Monitoring Direct means never having to be at the wrong end of computer timing latency. The more tracks and processing you do (in a 72 input system) the more Direct Monitoring becomes a requirement (you’ll see).

Remember, you can record your music tracks with the MONTAGE as audio interface. Then (reconfigure to) use the other audio interface to add your other instruments. Either audio interface can be used to playback your DAW Audio Tracks.