Short answer: the Harman Kardon Luna 2. It ranks #25 of 177 medium speakers by sound quality, rated 4.1/5, at $199.95. The Ultimate Ears Boom 4 ranks #112, rated 2.9/5, at $114.99, $84.96 cheaper, which does not close the gap in sound quality.
What the Ultimate Ears Boom 4 does well: A tough waterproof speaker that floats, with USB-C charging, app EQ and pairing with other UE speakers. It plays in stereo from a single unit, unlike the Harman Kardon Luna 2. Watch for: Not much improvement over the old ones.
The Harman Kardon Luna 2 is the better-sounding option. A stylish waterproof speaker with clear, spacious mids, tight bass that stays clean at volume, and stereo pairing with a second unit. The catch: Treble can sound bright and edgy, and it loses more output off-axis than some rivals.
Buy the Harman Kardon Luna 2. It is rated higher for sound quality, and saving $84.96 with the Ultimate Ears Boom 4 does not make up for the sound-quality gap.
Still deciding? The full Portable Bluetooth rankings cover every ranked option.
A tough waterproof speaker that floats, with USB-C charging, app EQ and pairing with other UE speakers.
A stylish waterproof speaker with clear, spacious mids, tight bass that stays clean at volume, and stereo pairing with a second unit.
Prices on this page were last checked October 31, 2026 at 7:11 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
As an eBay Partner, we may be compensated if you make a purchase.
Specifications Side By Side
| Ultimate Ears Boom 4 | Harman Kardon Luna 2 | |
|---|---|---|
| Price | $114.99 | $199.95 |
| Ranked | #112 of 177 in Medium Size Portable Bluetooth Speakers | #25 of 177 in Medium Size Portable Bluetooth Speakers |
| App | Yes | Yes |
| Battery Life | 15 hours (Manufacturer specified) | 12 hours (Manufacturer specified) |
| IP Rating | IP67 | IP67 |
| Power Input | USB-C | USB-C |
| Stereo | Yes | No |
| Omnidirectional | No | No |
| Weight | 1.4 lbs (620 g) | 1.6 lbs (735 g) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 5.1 | 5.4 |
| Dimensions | 7.2” x 2.9” x 2.9” (184 x 73 x 73 mm) | 8.5” x 3.3” x 3.2” (216 x 84 x 81 mm) |
| Drivers | 2x 1.57” (40mm) active drivers + 2x 1.81” x 2.57” (46.1 x 65.2mm) passive radiators | 62mm x 82mm woofer with passive radiator, 20mm tweeter |
| TWS | Yes | Yes |
| EQ | Yes (via app) | Yes (4 presets + custom) |
| Built-in Microphone | No | - |
| Power Bank | No | - |
| Aux Input | No | No |
| Maximum SPL | 85dBC (Manufacturer specified) | - |
| Digital Aux Input | No | No |
| Bluetooth Codecs | SBC | SBC |
| Strap | Yes (built-in loop) | No |
| MicroSD Playback | - | No |
| USB Playback | - | No |
| Frequency Response | - | 58Hz - 20kHz (-6dB) (Manufacturer specified) |
| Amplifier Power | - | 40W (25W woofer + 15W tweeter) |
Related Speaker Comparisons
More top alternatives to Harman Kardon Luna 2: