Make your macro on the rp6 or rp1 and on the button you will put that system macro first and then you can do your sound. Since your macro has started already the sound will continue to play as your macro goes. I have not tried this in a working system but in the preview it works and I can't see why it would not work.
Example:
line 1 is a system macro (system off)
line 2 is (maybe a page with a picture of the sound you want to use)
line 3 is the sound you want to use
line 4 is a delay long enough to run the sound
line 5 is the main page you want to go back to.

Let me know if this works.