Thanks Jim and ThoNoT. Now I have a great setup in which ableton uses my delta 1010 (with asio drivers!), going out via the stereo master to the mixer in the delta 1010 out 1/2. this is now my windows default audio device (which are picked up by OBS). my speakers are delta 1010 out 7/8.
first OBS picked up my audio once in a while, but after I switched "asio direct monitoring" in delta 1010 off the setup is perfect! Can stream everything from resolume AND ableton at the same time, even hardwired my FFT and SMPTE from ableton to resolume. Note: NO use of VAC or other virtual audio devices! How's that! (a manual including pictures of my setup is available soon)