If bi-amping is so great, why do some high end speakers not support it?

I don’t see a value in biwiring or biamping unless you have an active crossover. It does offer the possibility of using less expensive high quality amps to achieve a higher total power output to drive your speakers than the cost of a high powered amp with comparable stats of the two combined. . . Like others here I think that most manufacturers don’t want people to get into speaker design (building crossover networks) as most implementations will not deliver as good a final product as all of their research has shown. To implement a crossover, measurement software and hardware needs to be used. When executed properly the results can be stunning but often fall short due to the experience of the person trying to build it. I personally opted for the older 20.1 Magnepans exactly for the ability to build a crossover network and actively biamp the mains with matching amps. I played around with the slopes and type of crossover and found that their factory suggestions were best to start with. Custom crossovers have been implemented using REW and MSO but most affected is the bass region, little was corrected on the mains.

Thanks,
Steve

@co_jones

Isn’t the use of active sub-woofers bi-amping? (Yes)
I have tube amps, are people still using passive sub-woofers vs. powered ones, e.g. class-d? (I have 2 passive subwoofers with my mains with a Pass x250 powering and 2 high quality class d active subwoofers in room)
No one mentioned the quality of the active X-over. There has to be a wide range in quality. (Yes, I recommend that it operate at least 24bit/96kHz which resolves the range of human hearing) 
Like wise there was no mention of tri-amping. Wouldn’t leaving a passive X-over between the mid and high drivers and actively feeding the bass really be a hybrid? (Yes, Ex my 20.1 Maggies, there is an undefeatable crossover for the high/mid so one is really biamping mid/high and low) It can be done to defeat this crossover and add an additional channel and stereo amp  but the slopes and volume better be right or the tweeter will blow)

I agree, true balanced XLR are the best connections to reject all noise from the line. I use it in all but one (optical) connection. A high quality RCA can be used for short distances but one has to be careful to keep any noise inducing things away such as power supplies, cords, chargers, etc. Use balanced whenever possible. :)

- Steve