Viruskiller,

For multichannel sources, you would probably go with whatever the original format it is meant for since. The preferred method would obviously to pass through the 5.1 discrete channel format through a B-format recovery system, which would then be passed through a Ambisonic processing system which would allow unlimited channel capability. This has been proposed by ARA as a Ambisonic G+2 format, which would be compatible with standard 5.1 system, 2ch system or any system with the B-format recovery. If it is for pan-potted front/side/rear mix, instead of recovering B-format information, they could easily apply Trifield 360 deg around. I am not sure why Meridian is not providing this feature especially if they are the people pushing this format.

Ronomy,

Trifield might make a more of a soundstage than the original recording is exactly its purpose. Conventional music surround more or less converts a recording that's pan-potted between the L&R channel to be pan-potted between L-C and C-R (most seem to emphasize extracting L-R type of ambiance and try to place it somewhere in the rear to give you the impression of reverb). But that's not how our brain hear sounds.

A viola coming from the right side of the stage has almost the same loudness to our left and right ear, but due to it being off axis from center, the sound arrives at our ear at different times. In a multi-mic recording playback, the way a viola is presented as stage right is by having the right loudspeaker play louder than the left. Our brain combines the sound together to tell us that more of sound is coming from the right, but the the spatial localization part of our brain hears sound coming from the left speaker and right speaker, confusing that part the brain causing us to think the sound is coming from nowhere. So the original soundstage presentation is false already.

The way Trifield works, it tries to restore that part of the spatial localization that's missing in those flat 2ch recordings. In doing so, it allows our ear to localize sounds in all the ways it knows how to, so one method does not contradict with the other, allowing us to image instruments more naturally. (It also does the 2 to 3 ch conversion, but as described before, as a 3 speaker unison, instead of L-C and C-R).