Trying out the current "Linux 64 bit Stand alone Jack" version from
www.stereotool.com as well as the "stereo_tool_jack_gui_64_BETA1002-028" from the forum there seems to be an problem with jack.
When observing the output in QJackCtl the normal output and low latency output seem to work as intended. Only when selecting the FM Output it uses the same connection as the normal output out_l out_r.
The fm_l and fm_r never get connected, resulting in not being able to use the normal and FM Output at the same time.