I won't pretend to be an expert in the ever-expanding category of bluetooth audio, but I understand the appeal: After decades of being tethered to all variety of boxy, clunky or otherwise cumbersome hardware, technology has liberated us from those proverbially Gordian tangles of cables, if not the speakers themselves. Although we have more or less consummated the portability of playback devices, speaker cones and circuitry are confined to bulky cabinets, and—cheap computer speakers notwithstanding—require a separate amplifier to translate signals into noise (so to speak).
Which is precisely why I was interested to see that Paul Cocksedge's latest project, called the Vamp, not only offers wireless audio but a built-in 4–9-watt single-channel amp as well, all in a lemon-sized, USB-rechargeable device—effectively refurbishing any serviceable old speaker into a quasi-portable jamblaster.
And while I'm generally skeptical about such devices—in my experience, you might get some combination connectivity, audio fidelity, battery life and/or durability, but not all of the above—I have enough random old speakers around the house to make the Vamp a practical home audio solution.
The Vamp also has a standard 1/8” line-in jack for non-bluetooth audio; it's not yet possible to (wirelessly) tether a single music player to more than one of them, but it will include instructions to daisy-chain multiple speakers to a single Vamp, though I doubt it's possible to achieve true stereo with the diminutive device...