I've just gotten a Roland Studio Capture for a new audio interface. It's running, but I'm having trouble figuring out how the synths I've connected to the back operate as stereo instead of mono. My software plugins are fine in setting them in a stereo field, but the hardware synths aren't responding. 
There are stereo switches on the line ins which I've checked inside the Capture, but it doesn't seem to be doing any good. 
I recall having problems in the past with other equipment, and I switched the input cords and that worked. Not this time. Anyone have any suggestions about what to do?

From your description I do not fully understand your issue yet; so just a few ideas on what to check ...
 
... I assume you connected the hardware synths to neighboring input jacks (e.g. 5+6) and use a stereo Sonar track which receives both channels as input. In that case your synth should be recorded in stereo. Pls check on this is by recording a few bars, play it back soloed or check the waveform
 
... you might have input monitoring enabled on the Studio Capture, but inputs are not panned hard left and right, thus it sounds mono ????

Thanks, Rehab. I figured it out. Not only do you have to manually set the channels to stereo on the Studio Capture itself, but there is a screen setup on the computer (which was added when the driver was installed) which needs to be adjusted. So when I discovered that I quickly set it up correctly. Thanks again.