Clovis, The "B" terminal is simply a parallel connection internally splitting the same 2-channel output to allow for speakers in another room or outside(which feature is actually used on occasion). There's nothing whatever which would allow for any greater power or anything else by connecting those same two channels through separate speaker terminals to the low and high frequency sections of the speaker.
Furthermore, even a receiver/amplifier which has four or more output channels can't be used for true bi-amping, despite the claims of some sellers. Bi-amping, as the term implies, requires two separate amplifiers(not just separate output channels of the same amplifier), and also an external electronic crossover in front of the amplifiers to supply each amplifier with only the desired frequencies(the internal crossover in the speaker has to be removed or bypassed). Simply connecting previously unused output channels to the speaker accomplishes nothing significant; the power still comes from the one power supply section of the amplifier. Distributing the same available power through two sets of output transistors rather than one doesn't double the available power and can't increase it in any amount.
Enjoy the music, not the equipment.