Re: Paradigm Signature S8
That's a pretty serious speaker to run off a receiver, though I see no reason you shouldn't be able to. Their sensitivity is decent, though it annoys me that they call the impedance "compatible with 8 ohm". When you drop 6K on a pair of speakers you should get more detailed info than that. For optimal performance and speaker/amp interaction it is desirable to know how flat the impedance is across the spectrum and particularly what the minimum is. Their exclusion of that leads me to believe it fluctuates all over the place.
In the end, I think it is a bit foolish to spend that much on speakers and then let a receiver power them. I would definitely look into a good, solid, brute power amp at least for the front 3 channels. It doesn't need to cost a fortune. Something like an Adcom is a good place to start, or move up to Bryston or the like if the money is available. Really, the sky is the limit. Go with minimum 200 wpc. Just stay away from the ones which use electronic trickery to achieve their ratings. A big, heavy brute is probably the way to go.
If you spend 6K on a pair of speakers, it is entirely reasonable to spend 2K powering them.