My concern would be the subs hooked up to the XPA-5, or any other
amp that doesn't have gain controls. I'm just wondering if the volume on the subs will be too loud, and the Denon won't be able to turn the level down far enough. I say that because the gain on my sub
amps has to be turned down pretty far to get them within range that my receiver can get the levels evened out with my other speakers (which is true whether I'm running external
amps to my speakers or not).
I'm just throwing that out there.
I know that other people here run passive subs with external
amps, and they might know better.