Sample volume control works in swf, but not if the application is run directly from TGF2 or exported to an exe. Actually this is not a straight Flash-bug, since it actually works in Flash but not in standalone(confused) - anyway this seemed like the best place to report it so here we are.
To see the problem, open the swf file and click around on the "buttons" (gray rectangles with black outline) - you shouldn't be able to hear much since the sample channel 1 is set to only 10%.
Now open the .mfa and run it. As soon as you click on any "button" the sample channel volume jumps to 100% by itself.