Ok forgive me if I stumble thru this as I get ideas in my head and know what I am trying to say but have trouble saying it
You may be able to use a variable to get you back to your original zone. I am not sure how you navigate thru your zones/instances of Winamp, using Zone Set or Zone Next/Previous. If you use the Zone Set command you could add a Save to Variable command to that event that would write that zone number to a certain variable (CURRENTZONEVAR). So when you run the Vol events for each zone you add a Zone Set: %CURRENTZONEVAR% at the end and it should get you right back to where you were.
So on your event to switch to Zone 3 you would have:
Zone Set: 3
Save to Variable- Information: 3 Variable: CURRENTZONEVAR
event to switch to Zone 4 you would have:
Zone Set: 4
Save to Variable- Information: 4 Variable: CURRENTZONEVAR
To turn the volume up for the Winamp running on Zone 4 while you are currently on any zone would be:
Zone Set: 4
Volume - Increase:5 (or whatever)
Zone Set: %CURRENTZONEVAR%
You should never even know that you switched zones
Not I have tried this and it may or may not work..but now that I am saying it I think it would help me too
Let me know.