Essentially the ability to control multiple synths (or other MIDI input elements) from the same MIDI out.
This MIDI out would typically be a MIDI track but I suppose could be an FX's MIDI out(s) as well.
This could be implemented in a number of ways.
My favorite would be to allow the selection of any MIDI output as a MIDI input on synths or whatever.
Assign MIDI inputs to available MIDI outs. Currently MIDI outs must be assigned to MIDI inputs.
I suppose it could be a MIDI FX which you could insert into a MIDI track's FX bin. It would have N (pick a number or add outputs as needed) assignable outputs which you would route just like now.
It could be part of the Sonar core where any track has N outputs (see previous sentence about N).
As I said, I like doing the selecting on the INPUTs but the last two choices would probably be easier to implement given how Sonar works now.
Look at it this way.
If I have an EXTERNAL MIDI input like a keyboard( a MIDI out device), I can assign any number of MIDI track INPUTS to that keyboard. I hit a key and all the connected synths play that note.
I should be able to do the same with a track or any MIDI out signal within Sonar.
Please do not get into the 'this could cause feedback" thing. We are not children.