RoshRoslin
Power User
The biggest thing I would really caution people is to watch for phase cancellation and phase in general. Your tones will thin out incredibly if you sum up to mono and your tones are note in phase. I have spent tons of time de-stereo-ing client patches because of this result.
One quick way to check is run both L+R outputs into an interface that has a mono button (I use an apollo x8P or X4) and if you de-stereo your patches, leave output on the FM9 in stereo and hit the mono button and listen critically, you may hear that weird phase cancellation thing. This is what your tone will sound like if you use SUM L+R. If you can get this all sorted out, then you can use SUM L+R or Copy L>R with good results in mono.
One quick way to check is run both L+R outputs into an interface that has a mono button (I use an apollo x8P or X4) and if you de-stereo your patches, leave output on the FM9 in stereo and hit the mono button and listen critically, you may hear that weird phase cancellation thing. This is what your tone will sound like if you use SUM L+R. If you can get this all sorted out, then you can use SUM L+R or Copy L>R with good results in mono.