Looking for Suggestions for Audio in Kid Play Room

I realize that this request may sound a bit strange and certainly isn't a true HI FI need, but here's my situation.

Last November I purchased a pair of Audioengine A2 speaker for work. Due to a remodel at work I had them setup at home in our "play room" that is part of a large room that includes the kitchen. My main system in the living room that is on the same floor just around the corner.

Our house is about 1,300 sq-ft total and the downstairs is an L with the kitchen at the corner. The "play room" is connected to the kitchen with just a doorway to the living room.

The A2 speakers sounded really great and did a decent job of filling the space. It was really nice to have music in that room without having to deal with the main system. My wife inquired about getting another set of the A2's last night. Our kids are 1 and 19 months and the older one loves for music to be playing. He would specifically ask for us to turn the A2's on when they were at home.

The simple solution is to spend $200 for a second set of the A2 speakers. The main downside is the volume knob is on the back.

The second tempting option is to spend $400 a get the A5+ model that would be better suited for the larger space and include a front volume knob and remote. It would also be able to charge an iPod or iPhone (the most likely sources) with it USB connection. I may not be able to convince my wife to go for them due to both size and cost.

Our end goal will be to eventually get them wirelessly connected to my main system for a more whole house sound when playing background music.

I looked at some of the Sonos products and it looks like I'd be spending at least the $400 just to get something that sounds as good as the A2's for half the price.

Is there any other products that I should be considering? It needs to be active speakers or some type of dock to work.

I wish I could just get a single A5+ speaker to save space.

Any suggestions?
This is a new all-in-one wireless speaker system called the Woodbourne by Polk Audio $600.

Used Tivoli radio? (the Henry Kloss version)