A company called Mass Fidelity just launched a totally wireless whole house audio system called Core. Using Wave Field Synthesis technology, they get a much deeper and more realistic sound out of each speaker than the SONOS system does — and I should know this as I have a SONOS system in my home. But, the best part about Core is that the speakers are wireless AND batter operated — they can be carried around anywhere as they don’t need power. The battery lasts four to five hours.
The design is nicer than SONOS, too. Check out this demo I got at CEDIA 2015 here: