I use VSTi’s and a Roland RD-600 piano as a controller and external instrument. To be able to monitor the VSTi’s I have to enable MIDI Thru in the preferences. But my RD-600 doesn’t have a “Local Off” setting, so I get double notes when playing the piano and the piano sound when playing the VSTi’s.
Is it possible to enable MIDI Thru for VSTi’s and at the same time disable it for External Instruments?
Hi, I had a Brief view into the RD600 Manual I found in the Internet. Have a look 
To me it seems that you are free to select the midi-channels your internals Sound modules of the RD600 React to!
This means that you could use different midi channels on the two instruments and thus achieve what you Need.
HTH,
Ernst
Ah, and as far as I remember you can unclick the Little Monitor button. This will disable midi trough on the corresponding track.
Cheers, Ernst
Thankx for the tips Elien. Disabling the track monitor does the trick.