Frank,
Be sure that the AC power cords are the correct polarity. (This happens automatically with US cords, but the Schuko cords can be inserted with either polarity.) Use wood blocks under all of your components. Use wood blocks to keep all of your cables (power, interconnect, and speaker) off the floor. Use balanced interconnects. Use a Marigo mat when playing the discs. (The thinnest one will usually work well, but sometimes will cause some hiccups.) Don't connect a video system to your audio system. Bi-wire if your speakers will allow it.
Good luck,
Charles Hansen