Hello, we have found our customers to like the Cardas cables with these products.
You might try Kimber Hero. Easy to find and you should be able to resell quickly if it doesn't work out for you.
I had a 640C for several years and found that a good powercord made a real difference. I used a VH Audio Flavor 2 with good results. Like the Hero interconnects, the VH cord is in a "real world budget" range.
Ethos has some good ideas for you. The Kimber Heros should mate well with your player and amp. I am using Audioquest Diamondback interconnects and Type IV cables, and Shunyata Diamondback Power cable (complete coincidence on the naming convention!) with my 640C v2/AMC SS integrated system. The AQ inters provided more detail and air, but adding the power cord made the player more musical. I would have bought the VH power cable but needed a more flexible cord for my application.
I might recommend investing more of your available funds in decent power cords for your player and amp from Internet venders like VH, Audio Art, or one of the many power cords available from the cable company. You could then get quality budget interconnects and speaker wires from Blue Jeans Cables (http://www.bluejeanscable.com/). Blue Jeans uses quality Belden wires and connectors and doesn't charge an arm and a leg for their products. I am not saying these wires are as good as the host of higher tech and much more expensive products available, but they work as well or better than anything at their price-point or a little higher. Another option is Signal Cable who makes and sells inexpensive cables including power cords.
In any case, my experience has been that it is critical to get the power delivery right with Cambridge gear for it to achieve its full potential. Once you have done that, you will have a better chance to hear the effects of different interconnects and speaker wires downstream.
One last idea is to get discontinued AQ interconnects and speaker wires from HCM Audio at steep discounts for "new" wires.