Strange? Stupid? Are these synonymous with "professional multichannel"?
YES. You have to see that VLC tries to do a multichannel output where possible. However this was a completely uncovered terrain in the OSX documentation when we first did this ( Mac OS X 10.0 ). It was originally implemented for us by M-Audio.
Since then much has changed. The complexity has increased a lot and there have been many API changes. M-audio has not made any more contributions, and the VLC team itself lacks the required hardware and expertise to implement this.
I have the same problem (mono audio output on left channel only) but with a Metric Halo ULN-2. It's a FireWire professional audio card with six outputs and VLC 0.7.2 sees six mono output. The OS sound out sees output 1 & 2 as the principal output and audio comes rightly out as stereo with other apps (iTunes, DVD player, etc).
I will signal the problem to Metric Halo driver programmer to see what's his take on the problem.
The problem here that this is not a device you can just tell "Output these 5 channels. (at least not with our current implementation)"
Any contributions to this area of VLC are GREATLY appreciated and even more WANTED.