yep, playing with the audio files volume is something you can do, if it's really needed.
Rhyen : it's indeed planed. One of my customer asked but I didn't have time to design something so he got some schematics on his own. His design is great but uses too many I/O (still, he's not a EE and did a tremendous job on his DC 17). My plan is to make a peripheral unit that will be controlled just like the screen is, with messages (empty, reload to count xxx, decrease of XXX ammo etc). It will maintain the perfect synchro between sound and display. I even think it will be possible to have the screen AND the counter.
added to the TODO list :)