That would make no difference, the stereo speakers would still be playing full range.
You should be able to get great results with the Denon without need for the 6000A. Do you have the Audyssey MultEQ Editor app?
However, if you want to use the 6000A with mains and subs properly, I would not recommend connecting the Wiim straight to a miniDSP. I have owned several miniDSP products and used them as preamps or just processors. They work great for that and my Logitech Harmony has always worked well with them. The Flex would work much better as a preamp than the 2x4HD due to the screen and appearance. If you used the miniDSP connected straight to the Wiim you would have to use it for volume control. If you used the volume control of the 6000A it would only change the volume of the main speakers and not the subs connected to the miniDSP. Therefor the 6000A would only be used as a poweramp which is kind of a waste. Alternatively you could use the pre-out and power-in connections on the 6000A to connect the miniDSP as AudioLab intended:
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This way you could use the 2x4HD or even cheaper 2x4 with analog connections and still use the full functionality of your 6000A.