Seems like there are pros and cons to each.
Vertical: Each amp is only asked to drive one bass driver (the majority of the load), very high channel separation similar to monoblocks, easier to integrate than horizontal bi-amping, unbalanced rails an issue?, etc.
Horizontal: Can use 2 separate amps that are optimized for low and high frequencies, lower channel separation than vertical biamping or monoblocks, challenging to integrate?, etc.
The benefit I see with vertical is that the mids and tweeters have their own channels of amplification and in a well-built amp, one shouldn’t effect the other. Asking a single channel in an amplifier to deliver massive wattage for the mids while still being delicate enough to reproduce good highs seems like a tall order. With vertical, even if they share the same power supply/transformer, there should be some benefit as the channels are isolated from each other. That’s my thoughts on the subject and my listening impressions line up with that.
Vertical: Each amp is only asked to drive one bass driver (the majority of the load), very high channel separation similar to monoblocks, easier to integrate than horizontal bi-amping, unbalanced rails an issue?, etc.
Horizontal: Can use 2 separate amps that are optimized for low and high frequencies, lower channel separation than vertical biamping or monoblocks, challenging to integrate?, etc.
Bi amping is similar to bi wiring. You are simply running the power of the amps through the exact same internal crossover network of the speaker. This serves little to no benefit.
The benefit I see with vertical is that the mids and tweeters have their own channels of amplification and in a well-built amp, one shouldn’t effect the other. Asking a single channel in an amplifier to deliver massive wattage for the mids while still being delicate enough to reproduce good highs seems like a tall order. With vertical, even if they share the same power supply/transformer, there should be some benefit as the channels are isolated from each other. That’s my thoughts on the subject and my listening impressions line up with that.