These are not really the same size class, and that is the honest framing here. The Soundcore Boom 2 ranks #10 of 120 large speakers by sound quality at $99.99; the Harman Kardon Onyx Studio 9 ranks #15 of 113 boombox speakers by sound quality at $184.99.
The Soundcore Boom 2 is the louder, longer-running pick. A light, waterproof large speaker with deep bass for its size, a 24 hour battery and fun lighting. Alan Ross Reviews measured it at 105dB at full volume, against 101dB for the Harman Kardon Onyx Studio 9. It is rated for 24 hours of battery against 8 for the Harman Kardon Onyx Studio 9. At 3.7 lbs (1.68 kg) it weighs much less than the Harman Kardon Onyx Studio 9 at 9.3 lbs (4.2 kg). The tradeoff: Only a single midrange driver, so you only get stereo for the tweeters.
The Harman Kardon Onyx Studio 9 is the deeper-bass option. An elegant living room portable with balanced, smooth, non-fatiguing sound, app EQ, and stereo pairing for music lovers. Its bass reaches about 41Hz before falling 10dB, against 47Hz for the Soundcore Boom 2. The catch: It has no water resistance, aux input or USB playback, and its eight-hour claimed battery life is short for an outdoor portable.
Buy the Soundcore Boom 2 at $99.99 if you want a large speaker. Buy the Harman Kardon Onyx Studio 9 at $184.99 if you want a boombox speaker instead.
If water resistance matters to you, the Soundcore Boom 2 at IPX7 (brief submersion) holds up far better than the Harman Kardon Onyx Studio 9 at no water resistance.
Want more options? Browse the full Portable Bluetooth rankings.
Prices on this page were last checked November 7, 2026 at 7:34 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
| Soundcore Boom 2 | Harman Kardon Onyx Studio 9 | |
|---|---|---|
| Price | $99.99 | $184.99 |
| Ranked | #10 of 120 in Large Size Portable Bluetooth Speakers | #15 of 113 in Boombox Size Portable Bluetooth Speakers |
| App | Yes | Yes (Harman Kardon One app) |
| Aux Input | No | No |
| Bass Extension (-10dB) | 47Hz | 41Hz |
| Battery Life | 24 hours (Manufacturer specified) | 8 hours (Manufacturer specified) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC |
| Built-in Microphone | No | - |
| EQ | Yes | Yes (App EQ) |
| IP Rating | IPX7 | None |
| Bluetooth Latency | 125ms | - |
| Maximum SPL | 105dB (measured by Alan Ross Reviews) | 101dB (measured by Alan Ross Reviews) |
| MicroSD Playback | No | - |
| Party Mode | Yes (PartyCast 2.0 up to 100 speakers) | Yes (Auracast) |
| Power Bank | Yes (USB-A) | - |
| Power Input | USB-C | AC Power Cable (2-Prong) |
| Stereo | Partially (1 woofer) | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 3.7 lbs (1.68 kg) | 9.3 lbs (4.2 kg) |
| Bluetooth Version | 5.3 | 5.3 |
| Dimensions | 11.7” x 7.3” x 4” (297 x 185 x 102 mm) | 11.4” x 11.3” x 5.1” (289.2 x 287.5 x 130 mm) |
| Drivers | 120mm x 90mm woofer, 2x 20mm tweeters | 120mm woofer + 3x 20mm tweeters |
| Frequency Response | 45Hz - 20kHz (Manufacturer specified) | - |
| Amplifier Power | 80W | 50W RMS |
| Digital Aux Input | No | No |
| Lights | Yes | - |
| Strap | No | No |
| USB Playback | - | No |
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