@jrunr
I would never recommend horizontal bi-amping for efficient / sensitive speakers because it wouldn’t make sense. But for difficult to drive speakers it can be the most cost effective way to go with outstanding results. That is my experience. I don’t say it is the solution for everyone’s speakers but I challenge anyone who says it will never work in any situation.
I am only offering an alternative for you to investigate that I (and others) have had great success with. (If you lived close to central FL I would say to drop by my home and have a listen for yourself.)
To answer your previous question, horizontal bi-amping does not change the impedance of any speaker’s individual drivers, that is fixed. But it does change the impedance load that is presented to each amplifier. I would urge you to do some research on horizontal bi-amping and make a decision for yourself if it seems right for you. Don’t just take the word of advocates ..... or naysayers.
To make horizontal bi-amping work you have to have a couple of features in the system configuration.
1. A preamp that has two sets of outputs to drive two separate amps.
2. The bass amp has to have a built in gain control or you need to have a separate volume attenuation control device between the preamp and the bass amp.
Impedance of any speaker changes over the frequency range which is why a "nominal" impedance spec is not very useful by its self. Stereophile does present an impedance graph for your speakers that is helpful but I have never seen two impedance graphs presented, one for the top end and one for the bottom end in any review. Parts Express caries a software package to generate your own impedance graphs called DATS that cost about $100. I use it on all my speakers, those that can be bi-amped or not to see what is really going on.
Good luck.
