As they're being used in conjuction with the Marantz SR7005, I don't think you have to be careful about choosing the wrong cable (copper/silver).
If you don't want anything too bulky, QED's Original should work well and won't be too expensive, but if you want to push the boat out, try Chord's Rumour 2, which we use in our demo room, and I use at home in my own system. It might be a higher end cable, but it's not too bukly either. It's a silver coated copper which brings a little more detail through in the top end, and has a pretty neutral midrange with no blooming.