The following normal pan line generates errors in the Windows .exe of
Csound5:

a1, a2, a3, a4 pan asig, kpanx, kpany, 4, 1

This line works fine in CsoundAV (stereo or quad).

The error is different in a stereo and in a quad file:

In stereo, the run fails with a "Csound error in Csound.exe and will now
close" message.

In quad, the run continues (temporarily) with the error warning: "Error: no
legal opcode".

Art Hunkins

By the way...
What would be a reccommended procedure to generate a 5.1 compatible
audio file from Csound?
Just curious
Josep M Comajuncosas