Best iPad Software for Digital Streamer

My parents are extremely techonologically challenged so I'm looking for a great-sounding digital streamer that will connect to their music system (pre-amp) but that offers an easy-to-use, reliable and robust iPad software for controlling the streamer.

My research has pointed me to the Meridian Digital Media System (Sooloos) and to the Sonos system.

What else would you recommend?
Sonos is so easy to use I know how to use it. Highly recommended for those who do not want to learn all about digital hi fi. I use it for background music when I do not want to play a record.
Another vote for Sonos.