Mike, I believe by using a 'Y' connector out of the processor's center channel pre-amp all you are doing is taking the signal and splitting it to each amp which in turns provides the power for each speaker. By running both speakers out of one amp/receiver in parallel you'll be dropping the impedance of the
combined speakers thus requiring an amp that will be capable of handling the impedance drop of both combined speakers.
For example if I wanted to connect a 6 ohm VP150 in parallel with an 8 ohm VP100 the impedance will drop to 3.45 ohms, thus requiring an amp or receiver that will be capable of handling a 4 ohm or less combined speaker impedance.
Using two different amps I would then use the 'Y' splitter out of the processor's center ch pre-out and eliminating the impedance drop. You'd have a 6 ohm VP150 powered by one amp while the 8 ohm VP100 would be powered by the other amp. The 'Y' splitter does nothing more than split the signal to the amps that in turn powers the speakers.
Or something like that.
