Need help from smart people - biamping

Hi, I know some of you are electrical engineers or just knowledgeable - looking for your input. I'm looking at the option of bi-amping my speakers. One amp on the mid-tweet connection and an identical amp on the bass connection. Speakers are B&W N804s. Question is, if you do this do the two amps react to the loads as one amp would, or is it possible that if the two connections (drivers) have different impedences, the bass might be louder relative to the mid-tweet, or quieter? In other words, if the upper end has impedence of 8 Ohms and the amp puts out 100 w/ch at 8 ohms, and the lower end is at 4 ohms, and the amp 200 w/ch at 4 ohms, will this result in a problem in the resulting aural output than would have been experience with a single amp? Thank you.
I didn't read all the posts, so I don't know if anyone brought this up already. Have you considered verticle biamping? You will hear a difference using this method. Take your identical amplifiers and use one for each speaker. Biamp each speakers using the left and right channels.
Wow, thanks for all of the responses ! Most helpful. I was only considering horizontal biamping; the vertical approach as described did not even occur to me.
I was contemplating exact same configuration. With vertical passive bi amping, would the SPL increase at same volume level at preamp? If not, how about potential SPL increase capability with biamping at comparable before and after biamping?
Hi Nil,

In a passive biamp arrangement employing identical amplifiers, whether vertically or horizontally, any given frequency component of the input signal to the amplifiers will be subject to essentially the same gain as if only one of those amplifiers was being used full-range. Therefore there will be essentially no difference in the volume control settings that are used in the biamp and single-amp configurations. (I say "essentially" because there are some subtle effects that might result in extremely small differences, such as the very slight volume loss that can result from splitting the preamp's output signals, depending on the impedances that are involved).

MAXIMUM volume capability, before clipping occurs, may increase SLIGHTLY in the passive biamp configuration, to the extent that the output voltage swing capability of the amplifiers increases as a result of the fact that each amp would no longer have to supply current and power across the full frequency range. Or (less commonly) if the maximum volume capability of the particular combination of amp and speaker is limited by the current capability of the amp, rather than by voltage swing.

The main benefit, if any, would be with respect to sound quality.

Best regards,
-- Al
Hi Al,

Thanks that is exactly my thinking was. My preamp does have 'designed in' two sets of outputs (a balanced set and single ended set- I currently use only set of balanced at present). Not sure what that means to volume loss since both will pre-amplify the full signal still. Hopefully not much volume loss.

I was thinking that max volume capability increase, before clipping occurs, now would be close to 3db. Aren't we 'doubling' (than what it was) the power essentially to both m/t and l freq drivers? No? That is my primary goal. I am happy with the sound quality and overall tonal balance right now with one mono block pair.

In any case I would audition before buying an extra pair of amps but still there is shipping, extra pairs of same quality cabling, same tubes etc involved.

You do give enough technical info and reasoning for me to think about. Thanks!