Sanjay took my quote about remixing the front three channels out of context. I said I agreed it was useful for matrixed sound formats. I also believe it is useful for other formats when there is no centre speaker. So, if you can do it at all, why not be able to do it all the time for a 2.1, or 4.1 setup?

Contrary to what you say, the 990 does not support this in non-PLII modes because it does not allow specification of no centre channel. One way to do this is to allow a remix in all modes and, perhaps, set it to 100% center by default to left and right (50% each) for 2.1 and 4.1 configurations.

The need to remix stems from the speakers available, and not any defect in the discrete multichanel formats.

But, if you allow 0-100% remix in PLII why not in all modes, when there is a centre and 100% when there is none? Personally, when watching a movie alone in the "sweet spot" I prefer no centre channel dialog speaker.

The cylindrical dispersion patterns of planar magnetic speakers are not a "problem": they allow for greater sound levels at greater distances with less power because the SPL drops off by 3 dB for a doubling of distance, instead of 6. In their operational range of 150Hz to 40Khz, their distortion figures are amazing. Their dispersion pattern solves the problems of floor and ceiling bounce. Their one flaw is that they generally don't operate well below 250 Hz. However, they offer the big advantage of not requiring a crossover in the sensitive midrange area, common in small two-way and three-way speakers. They are usually combined with woofer arrays (like the Carver ALS, c. 1987 which combined three dipole 12" woofers with a 48" ribbon driver in each speaker), and tended to suffer from inefficiency problems (the Carver ALS were rated 86 dB/W/m) until modern magnets were developed (today 88-90 dB/W/m is common). Still, they like power, and clean power: cheap amps driven into clipping will destroy a ribbon.

The Radia 520i is designed to be crossed to a sub at 80 Hz, for example, and is rated 50-250 W.

However, the center channel dispersion pattern, if unaltered, will place dialog to the left of centre for right off-axis listners and vice-versa. Planar magnetic centre channel speakers contain difusing panels to offset this (and tend to be quite long, often more than a 32" set, to ensure off-axis response). This could also be achieved with a L-C-R blend, if available for other reasons. Either deal with the problem mechanically, or electronically.

The benefit of all of this is amazing sweet spot (which tends to be quite large, actually) imaging. In fact, I've heard PLII material over two stereo planar magnetic speakers with phantom sounds from the sides and rear, if the material and room is just right.