@vytis said:

Just wondering how you guys do surround panning? For example, panning a mono source around in a quadraphonic speaker setup?

Any ideas / links / suggestions would be much appreciated.

The two standard techniques are Ambisonics and Vector Base Amplitude Panning (VBAP). Note that both techniques are not limited to quadraphonic setups, or even panning in only the horizontal plane. I do not use Pure Data, so cannot help further; Google is your friend.

Regards,
Martin