It's also worth noting that -- likespeakers -- this one has a USB-out port so you can use it to charge phones, wireless headphones or other small devices (you'll need to supply your own Lightning or USB-C cable, of course). The internal battery is listed at 5,200mAh, which allows you to play the speaker at moderate volume levels for around 12 hours.
The "Boost" naming comes from a button on the speaker that boosts the bass using Anker's "patented BassUp technology." Once I engaged that boost I pretty much left it on, because the speaker sounds better with the boost activated -- something that's not always the case with "sound enhancement" modes. It takes the speaker from sounding a little flat and thin to sounding fuller and bigger with strong bass for its small size.
We fed it some pretty hard material -- music that often makes other small speakers distort -- and the SoundCore Boost did surprisingly well. The alt-J track "3WW" has some deep bass frequencies that the SoundCore 2 couldn't resolve without warbling, but SoundCore Boost handled the track without a problem, even at louder volumes (it does play quite loud for its size).
There's a little bit of presence boost, but the treble isn't accentuated enough to give the speaker a harsh edge. As I said, sound-wise this is in the same league as speakers like the JBL Flip 4 that cost a bit more. It's not quite on par in terms of design or build quality, but performance-wise it delivers.