OTOH, Rocketboost gets a lot of hype. Another one to look at would be Soundcast. This way you can choose the speakers you would like to use. Some decent little Polk bookshelf type speakers would probably suffice.
A couple of years ago I bought an Onkyo HT-S6300 7.1-Channel Home Theater Receiver and Speaker Package. It has been great!
This system has 2 "zones", which allow you to steam audio to zone 1 independently of zone 2. I didn't get any speakers to stream audio to zone 2, but would like to do so now. What would be some good choices for streaming audio to my Onkyo's zone 2? I'd really like it if those speakers were wireless, because I'm likely to want to move them to the back porch, kitchen, dining room, etc.