On the NuVo Grand Concerto I've used the Viking SLP-1 many times with good luck. NuVo tech support likes their products too, so that's a bonus.
[Link: vikingelectronics.com]If they want to get fancy you can even do the SLP-4 and record their favorite sports or tv theme on it. Never used it so I don't know the quality.
[Link: vikingelectronics.com]The last one I also added one more piece for a front door intercom/doorbell combo using Viking.
