Short answer: the Harman Kardon Luna 2. It ranks #25 of 182 medium speakers by sound quality (rated 4.1/5) at $199.95 and is still sold new; the EarFun Uboom Slim ranks #43 (rated 3.7/5) and is discontinued, so it is only an option used.
The Harman Kardon Luna 2 is the better-sounding pick. A stylish waterproof speaker with clear, spacious mids, tight bass that stays clean at volume, and stereo pairing with a second unit. It has an adjustable EQ, which the EarFun Uboom Slim lacks. The tradeoff: Treble can sound bright and edgy, and it loses more output off-axis than some rivals.
The EarFun Uboom Slim is the longer-running, lighter pick. A slim, affordable waterproof stereo speaker with long battery life that doubles as a speakerphone. It is rated for 16 hours of battery against 12 for the Harman Kardon Luna 2. At 1.2 lbs (560 g) it weighs noticeably less than the Harman Kardon Luna 2 at 1.6 lbs (735 g). It keeps a wired aux input, which the Harman Kardon Luna 2 lacks. The catch: Not as deep bass as others.
Buy the Harman Kardon Luna 2. It is rated higher for sound quality; the EarFun Uboom Slim is no longer sold new.
Still deciding? The full Portable Bluetooth rankings cover every ranked option.
Prices on this page were last checked November 14, 2026 at 6:17 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.
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Specifications Side By Side
| Harman Kardon Luna 2 | EarFun Uboom Slim | |
|---|---|---|
| Price | $199.95 | $79 Discontinued |
| Ranked | #25 of 182 in Medium Size Portable Bluetooth Speakers | #43 of 182 in Medium Size Portable Bluetooth Speakers |
| App | Yes | No |
| Aux Input | No | Yes |
| Battery Life | 12 hours (Manufacturer specified) | 16 hours (Manufacturer specified) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC |
| EQ | Yes (4 presets + custom) | No |
| IP Rating | IP67 | IPX7 |
| MicroSD Playback | No | - |
| Power Input | USB-C | USB-C |
| Stereo | No | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| USB Playback | No | - |
| Weight | 1.6 lbs (735 g) | 1.2 lbs (560 g) |
| Bluetooth Version | 5.4 | 5.2 |
| Dimensions | 8.5” x 3.3” x 3.2” (216 x 84 x 81 mm) | 2.6”H x 7.1”W x 2.6”D (65 x 180 x 65 mm) |
| Drivers | 62mm x 82mm woofer with passive radiator, 20mm tweeter | 45mm speaker drivers |
| Frequency Response | 58Hz - 20kHz (-6dB) (Manufacturer specified) | - |
| Amplifier Power | 40W (25W woofer + 15W tweeter) | 20W |
| Digital Aux Input | No | No |
| Strap | No | - |
| Bass Extension (-10dB) | - | ~63Hz |
| Built-in Microphone | - | Yes |
Where the Ratings Come From
- Harman Kardon Luna 2: reviews by Joy & Oluv’Sone, Mateusz Cholewa and Storytripper HD.
- EarFun Uboom Slim: reviews by スピーカー音質比較.
This comparison is generated from the ratings, specifications and measurements on each product’s own page, and it updates when that data changes. How we rank explains how each rating is decided.
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