Jetmph: With a Sunfire Cinema Grand, you would be neither vertically or horizontally bi-amping. That's because all of the channels are fed off of one common power supply. If running an amp with a dedicated power supply for each channel, it still wouldn't be vertically or horizontally bi-amping.
Vertical bi-amping implies that one power supply ( or amplifier ) feeds the left speaker while a separate power supply ( or amplifier ) feeds the right speaker. Horizontal bi-amping implies that one power supply ( or amplifier ) feeds the high frequencies of both speakers and a separate power supply ( or amplifier ) feeds the low frequencies of both speakers. Since every section of the speaker is being fed from one common power supply, there is no difference in this case as far as "vertical" or "horizontal" is concerned. So long as the power supply is big enough to feed all channels simultaneously, the biggest difference in performance will be increased dynamic headroom and the reduction of dynamic compression. The sonic results of this should be increased spl capacity and a more cohesive presentation, regardless of volume.
Since the power supply in this amp was designed to feed 5 channels of amplification and only four would be pulling on the power supply, i think that this type of installation with this specific amp should work great. The fact that Planckscale can experiment with the voltage / current outputs for the top end on his ML's is simply icing on the cake. Sean
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