Wireless speakers

Well, at first glance, I'd make sure you put them on isolation pads or else you could have broken china in that cabinet!
 
As for your REAL question, the last time I tried this was about 14 years ago and the reception was a bit spotty.  I can only assume/hope that the technology has improved considerably.  Another route to go (that I can't recommend) is DLNA.  Unfortunately, there aren't enough products out there that use this ability and, those that do, are stupidly expensive!

Yeah, I looked into the Sonos, at least until I saw the price tag and had some major sticker shock.
 
Eventually, I'd like a system where I can send audio from Media Monkey (the ability is supposedly there and will be more robust on their next upadate) to an external player.  I've helped a guy in Norway with a mobile app that can control Media Monkey (a media player that's much better than iTunes and made for people with very large music collections).  It now works on both a smart phone and a tablet which is very cool, but it will be perfect once I can send that signal to the player of my choice!