I would recommend getting the system together and breaking (re-breaking) it in. Then start thinking about cables. I use DHLabs as budget standard to break stuff in a decide where to go from their. If you find the top end a bit hot, then Cardas can calm them down. Transparent will pass through exactly what your components create.
Most important. Re-break in. I recently got and amp that had been used. It needed several days of play to get back to where it had been for shipment. But besides, you need a couple of weeks minimum to really understand what your "new" system sounds like. Then you can start thinking about upgrading wire.