Bi wire, bi speaker/amp

Right just wondering if having speakers that can take a wire pair for each speaker and an amp that has speaker a and b pairs is worth bi wiring ?

There are two ways to bi-amp. Horizontal and Vertical.
The former is uses two amps with each controlling one channel.
The second uses one amp for the higher frequencies and one for the lower.-I believe this is what you are asking about.
FWIW, I find this set up to be more problematic than beneficial, but I am sure others will disagree.
In any case, the preamp will provide the signal to each amp, that amp will relay the signal to the speaker. If you use the same amp for both high and low, there should not be a marked degree differing sound quality. But, if you use two different amps, you (theoretically) can influence sound reproduction.
As I mentioned, it can result in a new set of problems, but for some, it can offer positive results.
I forgot to add, that Cleeds offers another route to using vertically stacked amps- an active crossover. But, that would mean you aren't hooking up to a speaker with upper and lower binding posts- In which case the crossover is within the speaker.