From Myer's website : 40W Wireless Multi-room Speaker capable of delivering high-quality audio via AllPlay and the Panasonic Streaming App. Can be part of a multi-room speaker set-up that supports 'Party Mode' or 'Multi-zone' music playback. Very easy to set-up, no software installation required. 2-way (horizontal/vertical) free-standing design.
I signed up for Spotify Premium a week ago and wanted to be able to play music at home without having the computer or the TV on. Looked up http://spotifygear.com/ and saw two brands I thought that were affordable (Sony and Panasonic). Was looking at the Sony wireless speaker solutions where the Spotify Connect capability started from the SRS-X77 model ($449) and higher. Stumbled on this Panasonic SC-ALL3 with a big red SALE offer tag on Myer while searching. I thought $280 wasn't bad when compared to Sony's $449 but it got sweeter when there was an extra 25% off the $280 clearance price which brought it down to $210. May not be the newest but I think speaker spec wise it is a near equivalent (40W) to the Sony X77. No NFC quick connect, no bluetooth and no battery power but that is not what I am using it for.
Still a current model at Panasonic Australia Website: http://www.panasonic.com/au/consumer/home-entertainment/wire…
Not bad reviews on Youtube and Amazon. Got it today from Myer, set it playing, slept, woke up and it was still streaming. Don't have the issue of it disconnecting as some people did. Of course I set it to upgrade the firmware when I got it which took about 2 minutes to complete. It was a bit unnerving since the only thing indicating it was updating was a blinking orange power light and you have to wait until it became a solid orange light to indicate the update was complete. Other than that it is still streaming and I am controlling it (including speaker volume) via the Spotify app on my PC (or via the Spotify app on my Android mobile phone). Supports WiFi 2.4GHz and 5GHz frequencies (5GHz recommended by Panasonic).
From recent sale, Sony Htxt1 or htxt3 also able to meet your requirements I think. But this pana looks cool.