Hmm, I think I might have another problem. Those Poly Planar speakers are 4 ohm. Am I going to have a problem connecting to an average AV receiver? Don't most of them want 8 ohm speakers?
Many amplifiers can handle four ohm speakers, but you said these were to be run as a second pair from the same amp, correct?
Check the specifications for the amp closely as the impedance of the main speaker set may affect the amps ability to cope with four ohm secondaries.
If impedance load does turn out to be an issue, perhaps an auxiliary amp dedicated to the new speakers would be an easy work around. Compact digital amps are not expensive these days. I have been using a tiny
microFidelity Amphony amp for some outdoor speakers (those speakers are actually
outside).