OK, well thanks all for your replies!
Firstly, I think Henry has a point in that the Audio Physics/ room characteristics are on the leaner side. I also think that the PV-10 is also not allowing the full benefit of the Audions to come through.
Having said that, I have done some further listening

and have experimented with different speaker positioning. Although I am somewhat limited in how far I can go there, certainly managed to improved matters.
Upon reflection the Chord brightness/ thinness thing might just be a relative quality compared to the balance of the Parasound possibly tipped towards the other end of the scale. It's not painfully bright or anything.
So, sorry Pete, going to persevere with it for a bit longer
I'm sure in the long run it'll be a wise investment

Sounding better already