After all the helpful feedback from this forum I took the plunge and purchased dedicated music amps and used the pre-outs on the Sony. Musically the System shines, the Tannoy MX4's have never sounded so sweet and expressive. Surprisingly the 5.1 material is somehow more open and dynamic with the Arcam's performing the front speaker duties. From my experience I wouldn't heitate in utilising the pre-outs on the Sony receiver to upgrade both musically and in 5.1 mode. Thought I'd share my experience and thanks to all who helped me work out what to do.