I’ve found that having the center speaker up high creates a wall of sound effect that is actually quite pleasant for movies and even some music. Suddenly switching to the level tweeters especially below the screen can sound thin or anemic by comparison. To me the tradeoff is that the height matched (at least close) tweeters of a vertical array can have much better imaging and tonal balance. I say can because proximity to walls, TV screens and anything effecting first reflections can blow the improved imaging all to hell leaving the high mounted center actually sounding better by comparison.
Also as mentioned on at least one of the articles above many sound engineers spread some of the center channel information out to the mains to create a more seamless soundstage and take advantage of the usually better quality of the main speakers.
Part of my test I didn’t mention was popping in the Blu-ray HD audio sampler that came with my Oppo. I don’t care for most of the music but it sounds awesome. I thought this would be the most definitive example of quality audio I could use. I started listening switching back and forth between speakers and couldn’t hear a damn difference, even when I moved off center. So I stuck my ear up to the M80 and all there was barely enough coming out to keep the stereo image from collapsing to the nearest main. I have to say it is a beautifully mastered DVD as it made the front soundstage sound perfect with all three centers.
This brings up another point I should reemphasize. The example I give of sonic differences are things I have found that really highlight them. When testing in my apartment I found that probably 7 out of 10 movies sounded nearly identical with any center speaker which I figured was likely explained by the sound engineer blending the center channel information out into the mains. If you physically disconnect the center while leaving on in the receiver you can hear this better. Learned that trick from John when testing out what PLIIx does with surround sound.
The biggest issue for me using a different center for music is mostly imaging. The tonal differences are usually highlighted when using PLIIx to create the center channel. However, this can be mitigated somewhat by adjusting the “wide” parameter, in effect being your own sound engineer.
