You'd be forgiven for wondering why Sonos has bothered bringing out a wireless sub woofer in the shape of the Sonos Sub.

If you've ever heard the dinky Play:3 speakers or their larger siblings, the Play:5, then you'll know what we mean – if you can get that kind of sound from a bookshelf-friendly set up, what's the point of adding a hulking great 'woofer to it?

That's what we thought too. But then we heard it. And suddenly we wanted to have a massive party just to put the thing through its paces.

We can sum it up thusly: Play:3 alone: good. Play:3 with sub: brilliant.

Let's take a look at the thing: it's about the size of a desktop PC tower with a hole in the middle – this is important, we'll come back to that hole. The sample we played with had the gloss-black finish, which meant it was intimidatingly shiny – Sonos tells us that it's been lacquered eight times and buffed for sixteen months (or something) so, you know, that's good gloss. For the fingerprint-phobic, there'll also be a matt-finish edition coming in September.

The unusual design allows for the sub to be placed in all sorts of places – against walls, under sofas… wherever works with your décor.

Because the force-cancelling speakers are housed in the middle gap, it pushes the sound out all around. Sonos has designed them specifically for this cut-away, so rather than being round, the speakers are racing-track shaped.

When you see the Sub in action those speakers are going like the clappers, bouncing in and out like an over-excited rapper in his first pimped-out hydraulic lowrider. It does look cool, but what if you wanted to rest a cup of tea on top as you so often do while listening to bassy European trance at the maximum possible volume?

Never fear, tea-loving party people: the vibration is almost entirely contained by the unit so you can barely feel a thing outside the casing – really, just the minimal vibration. That means you can pop the sub anywhere and not worry about annoying vibration sounds interfering with playback or disturbing your décor.

The sound is impressive. Beware, Play:3 and Play:5 owners: by toggling the sub on and off from the Sonos controller app, you risk ruining the standalone speakers forever.

Immediately you'll hear added warmth in the playback, and the sound becomes much fuller, better rounded by the addition of the extra bass heft. Toggling back to the stereo-speaker set up alone, music began to sound almost tinny. The addition of the sub makes you want to get up, turn it up and dance.

Set up, incidentally, is embarrassingly easy. Pair the sub with your Sonos Bridge then tweak the settings using the controller app and some test tones, and you're away.

The biggest downside is that all that bass comes at a fairly hefty price. The glossy edition comes in at £599 ($699) while the cheaper matt Sub isn't available until October when it will cost £499 ($599).

And we're not completely convinced by the gloss finish – it's going to need some serious grooming, we imagine – but that could be because it doesn't exactly match our décor darlings.

We can't vouch for its longevity after our brief time with the Sonos Sub, so you'll want to check out our full review in a week or two.

But first impressions? For a big sound from an easy set-up with unobtrusive speakers, we have no hesitation in giving the Sonos Sub the thumbs up.