Anyone prefer horizontal bi-amping their monos?

It can be done both ways with great results.  I go back and forth between 2 and 4 amps depending on which pair of speakers I'm using. To me and those who hear my system it is fantastic. Nothing messy at all using 4 amps. Even on Tannoy Legacy Arden.  It's a game changer. Check out my system. 

@re-lar-kvothe thanks for sharing the diagram. Clears up any confusion.

"A picture is worth a thousand words"

No so fast… that is two stereo amps.
The OP has 4 mono amps, so some mention needs to take place that the amps are split down the middle into two parts.

And a further mention of what the active cross over is, and how it works.

Pretty certain that the OP has 2 Carver stereo amps per previous posts in other threads.

DeKay

1 amp for the left, one for the right, use long XLR cables and ultra short speaker cables 

The best part of my tri-amped (outboard electronic x-over) is that the bass can do what it wants and the mids and highs have no clue.  Stay in the same amp family and it will work out.  

Regards,

barts