The QS10 can certainly go louder than the QS8 but that's not why I suggested it. The QS10 has higher fidelity and greater dispersion. It's a more expansive, fulfilling listening experience. It could be your wife is objecting to the not-so-good sound of the QS8.
One other thought. It's quite possible your wife is objecting to distortion from your Denon that may not be obvious until you wire in the 1500. You'd be surprised how happy your ears-brain are with high sound pressure when it's clean.
The 1500 is more costly mostly because the toroidal transformer doubles as a luxury cruise liner anchor and the capacitor bank is large enough to power Doc Emmett's Mr. Fusion Home Energy Reactor.
Remember you can trade in your current gear to offset your cost.
