It seems to be well-enough documented which pin is the S/PDIF output on the rear connector to the MX25, but which pin is the S/PDIF input on the MX300?

I know the S/PDIF output can be routed into a SoundBlaster Audigy 2 via the AD_EXT connector; however, in this system, I have the front drive bay for that installed, so that connector is in use here. It would be very convenient if I'd be able to route the MX300 into the digital CD input on the Audigy 2, and simply move the digital CD input into the MX300 (at least, hoping it'd route it to the S/DPIF output).

I've enabled it in the mixer with a registry edit; just need to find the pin, now!