Monoblocks vs Vertical bi-amping vs Horizontal bia

ALL: Thanks for your input thus far. I've re-read Dennis Had's white paper on Vertical bi-amping (which he says has a stereo amp dedicated to one channel) and his argument is: (1) one stereo amp per channel equals 4 channels of amplification, and (2)a 40 watt/ch amp stereo amp in a bi-amp config. will outperform a 80 watt mono amp driving all drivers together. I'll have to trust his judgement as he makes both monoblocks and stereo amps. . .

CONCLUSION: vertical biamping is better than monoblocks. Which still leaves open for discussion vertical vs horizontal biamping. . . It would appear from all your posts that horizontal biamping is more "tricky" in that the amp for the bass across both speaker channels will have to have much more power than what is required for the mids/tweeters so using 2 diff. amps will necessitate a gain attentuator. So all things equal, I'd say that it'd be easier and perhaps less costly to go the vertical biamp route. Your thoughts?

All depends on a few factors as to what might be cheaper.

How much power
Quality of amps
Class Amp A-A\AB-D
Cables
XO unit

Horizontal would be the more economical choice.For the Bass you need like 2-3X more power then the Mid & Tweeter's or individually.The Tweeters are the least power consuming driver's.

probably there are more variables that determine cost.I want to go vertical,but I have to wait,see and decide then buy.

I've found that with highly transparent & revealing speakers like my Apogees, vertical bi-amping is the way to go. Mixing'n matching amps between the bass panels and the midrange/tweeter ribbon has always lead to a dynamic discontinuity between the drivers. While it may sound great with sedate music, when things got rough and tumble, one driver would always "stick out" of the presentation relative to the other. This has been true with the various cone'n dome speakers I've had as well (Vandersteen in particular).

The only exception to this in my experience has been with subwoofers. Don't forget adding a powered sub (with the amp and active x-over being either internal or external to the sub)IS active bi-amping. I would also encourage anyone who has a powered sub and using a good active x-over (again internal or external to the sub), to take the low level high pass signal, split it and passively bi-amp with it. By cutting the lows from the midrange/tweeter signal, you're putting considerably less stress on that amplifier channel and the passive x-over that feed the midrange and tweeter. The passive x-over in particular will be much better behaved as the coils and caps will be much less prone to saturation since they are'nt seeing the full range signal anymore. The sonic differences are immediate and obvious, even with less than the best speakers (actually, the difference tends to be more readily noticable with the lower-FI speakers as the x-overs that feed the midranges and tweeters are not that well built and readily appreciate the leaner signal diet).

The above high pass signal stuff is all relative to passivley bi-amping the speakers full range. You still have the signal filtering advantages even if you don't passively bi-amp with the highpass signal from an active sub x-over....It's just that when you do, things go up a couple of more notches over a single amp than you might have expected.