Prime Day delivers, with this excellent Ultimate Ears Boom 4 sale headlining my list of the best audio deals of the week. Check out our Prime Day Live Blog post, our Best Bluetooth Speakers guide, and our ultra-roundup of the Absolute Best Prime Day Deals for a cascade of sales. The Boom 4 (8/10, WIRED Recommends) follows an impressive legacy in the world of Bluetooth speakers. The speaker's sound is smooth and clear, with more refinement in the subtle details than most speakers we test, while still offering solid punch at high volume. The bass isn't as beefy as its larger sibling, the Megaboom 4 (also on sale for Prime Day) but it's much more packable to let you take it virtually anywhere.