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The Pioneer VSX-519 does not have enough speaker outputs to run two pairs as A/B speakers.
The VSX-819 does have enough speaker outputs to run two pairs as A/B speakers, but the listed minimum impedance with both pairs running is 12 Ohms. The Ushers are 8 Ohms nominal, and I can't say that no damage would occur if you run both pairs on the VSX-819.
The VSX-1019 would allow you to connect both pairs with a listed minimum impedance of 6 Ohms, so you'd be set.