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That receiver does not appear to have preamp outputs so you can't use it with an external amp. The NAD is an integrated and wouldn't really fit what you're describing, though it could be used that way - an actual external amp would be a better choice, though as mentioned, it won't work regardless with that receiver. Rather than getting two devices, get one better receiver to handle the speakers properly.
5 Ohm isn't too bad considering they are 92dB sensitive, but you'll still want a more hefty amp than either of those listed IMO, though it depends on how loud you intend to listen. Something in the 100W actual output range.
For sub, I'd be looking at the SVS SB2000 or HSU VTF-2 Mk5 without question:
https://www.svsound.com/products/sb-2000
http://www.hsuresearch.com/products/vtf-2mk5.html