Something that has confused me for a long time: my sound card has one output, so I am limited to 16 channels. So, I can have up to 16 instruments in a single instance of, say, Play. I can set all 16 channels to a different pan parameter. Now, if I add a second instance of Play (or other VSTI), I can use different instruments. However, I am still limited to just 16 different pan parametrs, right? I know I can use controllers to force a change of pan, but there can never be more than 16 different pan parameters in effect at any given time, right? Remember, I'm limited to 16 channels on my soundcard. I can't seem to get this across to people on the East West Forum. They keep talking about multiple instances of Play. I get that. but unless I have an interface with more than one output, I'm only getting 16 channels. Sonar will default any pan parameter to the first instance of a given channel. For example, if flutes are on channel one, and I set pan to 68, and then I put a banjo on channel one, and set pan to 80, Sonar will revert to the pan setting for the flute. I could change it with a controller, but I would then need to change it back to 68 the next time the flutes play. Am I understanding all this correctly? If not, can somebody please enlighten me?

If two instruments are on the same MIDI channel, then they will both receive any controller messages designated for that channel. So yes, if flute and banjo are both on channel 1, the CC10 (MIDI pan) event will indeed be routed to both of them and their pan positions will track together. The only way to pan them independently would be to assign them to separate MIDI channels.
 
Don't confuse instrument slots in the sample player with MIDI channels, as they're two different things. The sample player lets you play up to 16 different instruments, but each can be assigned to any of the 16 MIDI channels.
 
Sometimes, you do want to assign two or more instruments to the same MIDI channel for stacking. But if you want to control pan independently for multiple instruments, each will need to be on a separate MIDI channel. I'm not an E/W user so I can't tell you specifically how to do that, but I'm certain that you can.
 
None of this depends on your sound card, which would only limit the number of external hardware devices you can drive from the sound card's physical MIDI port. It has no effect on software synthesizers.

Thank you. Can I quote you to the EW forum?