ok. I figured I have the Left and Right SID modules wired up to the core correctly, because I am getting audio from both left and right channels. but the audio produced (no matter how much tweaking I do through the menu interface) it still comes out as mono. My mixer has a left and right audio level readout and I am getting audio from both channels, however there is no noticeable difference between the channels. I use a stereo cable that splits to left and right channels that plugs into my mixer. On the output, continuity checks out by testing the Tip to the right module and the Ring to the left module.
I would also recommend loading up one of the example Drum Sequencer patches since they produce different sounds on the left and right channels (SIDs) so you can see if you are, indeed, hearing both SIDs.
And if you plug in both SID, l & r separatly into your mixer does that work? This seems like a connection of audio line problem. Are you absolutly sure you soldered both SID audio channels right?