Desperately seeking help, Sonar X1 expanded with Garritan's Aria soft synth

There are a couple key things you need to do to get Aria player to play nice with SONAR. Randy Bowser has posted a lot about GPO, JABB and Aria Player, so try Googling those search terms with his username, rbowser, against site:forum.cakewalk.com, and I think you'll find a lot of good stuff.

To get you started:

Unlike most synths, Aria uses CC1 (Mod Wheel) to control instrument volume. So you need to have at least one CC1 message in every track to establish an initial volume when playback starts, and you have to disable "Zero controllers when play stops" under MIDI preferences so that SONAR won't silence the instrument by setting CC1=0 every time you stop playback.

From there, it's basically a matter of ensuring that you're either recording notes with the correct channel sent by your controller, or setting a "forced" Output channel on each track to drive each instrument independently, and creating audio tracks to host the audio output of each instrument (or group of instruments) as assigned in Aria.

I haven't used Aria for a while, and am just writing off the top of my head, so that's just a rough outline. As I said, you'll want to Google and read some of Randy's stuff, especially regarding the use of CC1 and CC11 (Expression) to control instrument volumes.

Press "p" for preferences.

Click on midi in the "project" section.

Uncheck the "zero controllers when play stops".

I'm pretty sure that's the problem.

HTH