Well I can't bump this old as dirt thread http://chipmusic.org/forums/topic/1443/ … pro-sound/ so I started a new one
Reference pic 
I recently put a headphone jack in my GBASP under the led lights however I can't get the internal speaker to mute without mangling the jack even further which makes the pro-sound mod appealing to me but I'm curious, what's c24 and why does it need to be connected to pin 6 on that chip for the internal speakers?
My jack doesn't have a GND switch but a Lout/Lin Rout/Rin switch (for killing conventional speakers) but since the speaker is mono could I feasibly connect the Chips PIN 6 to ROUT on my jack (which would connect it to RIN when there's no headphones plugged in) Or would this make the speaker function improperly like I can only hear the Right audio from a game instead of whatever/however mono sound normally operates (I'm pretty ignorant about audio stuff).
Headphone jack I installed for reference (i cut it down to 15mm long removing the Lout pin)
http://www.mouser.com/Search/ProductDet … SMT4BHNTRX
I chose it because it was super slim and I could fit it up high and out of the way of my hands while I play games without having the GBA SP missing any screws.