My main SNES died a few days ago so I decided to mod the backup. After hearing a few tales of people having trouble soldering to those awkward pins on the DSP I decided to look for some better locations to solder to and I did.
My SNES (and most likely almost every one out there) has a DAC IC. This IC must be fed from the same lines that we tap for the mod so after googling up the DAC's datasheet and metering out the connections between the DAC and DSP confirmed this was the case. The DAC provides ILRCK, ISCLK and SDIN (using the terms on the wiki article). Obviously +5v and GND can be had there also but I didn't use them (more on that later). For the RESET and OMCK signals the nearby expansion connector provides them on pins 19 and 21 (and another convenient GND point).
IMO the DAC is far easier to solder to and I guess if you manage to kill it all you loose is sound and pretty much any 16 bit stereo DAC could replace it (with re-wiring of course
I've attached a (rather poor) pic of the mod in my replacement with the various pins highlighted:
A - Reset
B - Master Clock
C - Sample Clock
D - Sample Data
E - Left / Right Clock