Originally Posted by lowboy
Is there a way to configure the extra outputs to carry the main stereo feed instead of the side/rear/etc? Failing that, will a passive splitter cable degrade the sound?
You can use stereo upmixing to multiple channels, check the settings in the Xonar audio center. However, depending on your drivers, Windows version, and the audio API your programs use, it might not always work, sometimes you could only get audio on the front channels.
A passive splitter should not in theory degrade the sound, the front channel output jack of the card could drive 10 parallel amplifiers without having issues with the increased load. The only potential problems are higher risk of ground loops with more devices connected (if you do not hear any interference noise or hum, then there is no such issue), and that the input of an amplifier that is turned off may sometimes cause distortion in the other (if both the receiver and the M-stage are turned on all the time, then this obviously does not happen).