At $50/£50, the Amazon Echo Dot is an affordable Alexa access point, but as far as its speaker is concerned, the thing's a bit of a pipsqueak. And forget about picking it up and taking it with you -- for that sort of portability, you'll need to spend more than twice as much on the Amazon Tap (not available in the UK).
Well, a company called Ninety7 thinks it has a solution for both shortcomings. It's called the Vaux (pronounced "vox"), and it's a combination speaker and battery base that costs $50. Pop the Echo Dot into place up top, and it'll pipe its sound directly through the Vaux's speaker. And, thanks to the built-in battery, you can unplug it and take it with you for up to 6 hours of wireless playback.
In that sense, Vaux lets you upgrade your Echo Dot into something closer to the Amazon Tap -- and given that a Vaux and an Echo Dot together cost about $30 less than the Tap does, that's a pretty good deal.
Still, there a couple of trade-offs to keep in mind. First, there isn't a quick, convenient charging dock for the Vaux like you get with the Tap -- you'll need to plug it in using your Echo Dot's existing power cable. Second, the Vaux's sound quality, though easily loud enough to fill a room, sounded a bit distorted to my ear at max volume, and it wasn't as crisp-sounding as the full-size Amazon Echo (I'd even rank it just slightly beneath the Tap). And finally, though it's probably fine for most needs, the Vaux's battery life isn't the best I've seen, coming in right at 6 hours of full volume playback in my tests. With the Tap, you can expect closer to 8 or 9 hours, and with an Echo Dot battery base that doesn't include a speaker, like the Fremo Evo, you might be able to get as much as 12 hours or more.
For those reasons, I'd probably spend that extra $30 on an Amazon Tap as opposed to buying an Echo Dot/Vaux combo. But if you've already bought a second-gen Echo Dot and wish you could take it with you around the house, then Vaux is a perfectly reasonable upgrade.