Short answer: the Harman Kardon Onyx Studio 9. It ranks #15 of 98 boombox speakers by sound quality (rated 4.1/5) at $189.99 and is still sold new; the Soundcore Motion Boom+ ranks #68 (rated 2.9/5) and is discontinued, so it is only an option used. The Soundcore Motion Boom+’s replacement, the Soundcore Boom 2 Plus, is rated 3.6/5 at $179.99.
The Harman Kardon Onyx Studio 9 is the better-sounding, deeper-bass pick. An elegant 9.3 lbs (4.2 kg) living-room portable with a measured 41Hz -10dB bass point, 101dB maximum level, three tweeters, app EQ, stereo pairing and Auracast multi-speaker linking. Its bass reaches about 41Hz before falling 10dB, against 52Hz for the Soundcore Motion Boom+. 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.
The Soundcore Motion Boom+ is the louder, longer-running pick. 80W stereo from dual 30W woofers + dual 10W tweeters with titanium drivers for treble clarity. Alan Ross Reviews measured it at 108dB at full volume, against 101dB for the Harman Kardon Onyx Studio 9. It is rated for 20 hours of battery against 8 for the Harman Kardon Onyx Studio 9. At 5.3 lbs (2.4 kg) it weighs much less than the Harman Kardon Onyx Studio 9 at 9.3 lbs (4.2 kg). Watch for: Default presets are all warm sounding with rolled off treble.
Buy the Harman Kardon Onyx Studio 9. It is rated higher for sound quality, and the Soundcore Motion Boom+ is discontinued, so it is only available used.
There is a real gap in water resistance: the Soundcore Motion Boom+ at IP67 (brief submersion) against the Harman Kardon Onyx Studio 9, which has no water resistance.
Looking for alternatives? See the complete Portable Bluetooth rankings.
Specifications Side By Side
| Harman Kardon Onyx Studio 9 | Soundcore Motion Boom+ | |
|---|---|---|
| Price | $189.99 | $122.42 after $40 coupon, Discontinued |
| Ranked | #15 of 98 in Boombox Size Portable Bluetooth Speakers | #68 of 98 in Boombox Size Portable Bluetooth Speakers |
| Bass Extension (-10dB) | 41Hz | 52Hz |
| Maximum SPL | 101dB (measured by Alan Ross Reviews) | 108dB (measured by Alan Ross Reviews) |
| IP Rating | None | IP67 |
| Power Input | AC Power Cable (2-Prong) | USB-C |
| Stereo | Yes | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 9.3 lbs (4.2 kg) | 5.3 lbs (2.4 kg) |
| App | Yes (Harman Kardon One app) | Yes (Soundcore app) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC |
| EQ | Yes (App EQ) | Yes (App EQ) |
| Party Mode | Yes (Auracast) | Yes (PartyCast up to 100 speakers) |
| USB Playback | No | No |
| Bluetooth Version | 5.3 | 5.3 |
| Battery Life | 8 hours (Manufacturer specified) | 20 hours (Manufacturer specified) |
| Amplifier Power | 50W RMS | 80W |
| Dimensions | 11.4” x 11.3” x 5.1” (289.2 x 287.5 x 130 mm) | 15.1” x 5.1” x 7.7” (384 x 130 x 196 mm) |
| Drivers | 120mm woofer + 3x 20mm tweeters | 30W: Dual drivers |
| Digital Aux Input | No | No |
| Aux Input | No | Yes |
| Strap | No | Yes (detachable strap) |
| Aux Latency | - | 17ms |
| Bluetooth Latency | - | 33ms |
| Power Bank | - | Yes (USB-A, 5V/2.1A) |
| Built-in Microphone | - | No |
Related Speaker Comparisons
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- EarFun Uboom X vs Harman Kardon Onyx Studio 9
- Harman Kardon Onyx Studio 9 vs Tribit Stormbox Blast
- Harman Kardon Go + Play 3 vs Harman Kardon Onyx Studio 9
- JBL Partybox Encore 2 vs Harman Kardon Onyx Studio 9
- JBL PartyBox On-The-Go 2 Plus vs Harman Kardon Onyx Studio 9
Prices on this page were last checked October 12, 2026 at 4:13 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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The Two Speakers In Full
Harman Kardon Onyx Studio 9: $189.99 Amazon $189.99 eBay
Older models: the Harman Kardon Onyx Studio 8 (ranked higher, rated 4.1/5), the Harman Kardon Onyx Studio 7 (ranked higher, rated 4.1/5), the Harman Kardon Onyx Studio 6 (ranked higher, rated 4.1/5), the Harman Kardon Onyx Studio 5 (ranked lower, rated 3.9/5) and the Harman Kardon Onyx Studio 4 (rated 3.3/5). See every Harman Kardon Onyx Studio generation.
Pros: An elegant 4.2kg living-room portable with a measured 41Hz -10dB bass point, 101dB maximum level, three tweeters, app EQ, stereo pairing and Auracast multi-speaker linking. Reviews praise its balanced, smooth presentation and non-fatiguing treble, making it a more music-focused choice than most party speakers. Measured bass extension of 41Hz (-10dB).
Cons: It has no water resistance, aux input or USB playback, and its eight-hour claimed battery life is short for an outdoor portable. Bass is less deep than some earlier Onyx Studio models, while the slightly recessed mids and rolled-off top end mean it is not the most open or detailed option; it still charges from an AC power cable rather than USB-C.
Full Harman Kardon Onyx Studio 9 review and specifications →
| Released | Dec 2024 (1 year ago) |
|---|---|
| Amplifier Power | 50W RMS |
| App | Yes (Harman Kardon One app) |
| Aux Input | No |
| Bass Extension (-10dB) | 41Hz |
| Battery Life | 8 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC |
| Bluetooth Version | 5.3 |
| Digital Aux Input | No |
| Dimensions | 11.4” x 11.3” x 5.1” (289.2 x 287.5 x 130 mm) |
| Drivers | 120mm woofer + 3x 20mm tweeters |
| EQ | Yes (App EQ) |
| IP Rating | None |
| Maximum SPL | 101dB (measured by Alan Ross Reviews) |
| Omnidirectional | No |
| Party Mode | Yes (Auracast) |
| Power Input | AC Power Cable (2-Prong) |
| Stereo | Yes |
| Strap | No |
| TWS | Yes |
| USB Playback | No |
| Weight | 9.3 lbs (4.2 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
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Soundcore Motion Boom+: $122.42 after $40 coupon Discontinued Amazon $122.42 eBay
Newer model: the Soundcore Boom 2 Plus, ranked higher, rated 3.6/5, released May 2024. It adds built-in mic and AAC. See every Soundcore Boom generation.
Pros: 80W stereo from dual 30W woofers + dual 10W tweeters with titanium drivers for treble clarity. 13,400mAh battery for 20 hours (12-15 at high volume). IP67 waterproof, floats, rugged build inspires confidence. Bluetooth 5.3 multipoint pairing, Soundcore app EQ, PartyCast 2.0 mode. USB-C input, USB-A output for powerbank. Measured bass extension of 52Hz (-10dB).
Cons: Default presets are all warm sounding with rolled off treble. Will need a custom EQ to get closer to neutral. A shrill sounding 6kHz peak comes out when volume is above about 60%. Not much deeper bass than a Soundcore Motion Boom and a lot less deep bass than other speakers in the class. Discontinued.
Full Soundcore Motion Boom+ review and specifications →
| Released | May 2022 (4 years ago) |
|---|---|
| Amplifier Power | 80W |
| App | Yes (Soundcore app) |
| Aux Input | Yes |
| Aux Latency | 17ms |
| Bass Extension (-10dB) | 52Hz |
| Battery Life | 20 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC |
| Bluetooth Latency | 33ms |
| Bluetooth Version | 5.3 |
| Built-in Microphone | No |
| Digital Aux Input | No |
| Dimensions | 15.1” x 5.1” x 7.7” (384 x 130 x 196 mm) |
| Drivers | 30W: Dual drivers |
| EQ | Yes (App EQ) |
| IP Rating | IP67 |
| Maximum SPL | 108dB (measured by Alan Ross Reviews) |
| Omnidirectional | No |
| Party Mode | Yes (PartyCast up to 100 speakers) |
| Power Bank | Yes (USB-A, 5V/2.1A) |
| Power Input | USB-C |
| Stereo | Yes |
| Strap | Yes (detachable strap) |
| TWS | Yes |
| USB Playback | No |
| Weight | 5.3 lbs (2.4 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Joy & Oluv’Sone: Soundcore Motion Boom Plus & Earfun UBoom X - sound test More from Oluv’Sone →
- Alan Ross Reviews: Tribit Stormbox Blast Review vs Soundcore Motion Boom Plus - cheap bass! More from alanrossreviews →
- Alan Ross Reviews: Anker Soundcore Motion Boom Plus vs JBL Xtreme 3 - Extreme review!
- Alan Ross Reviews: Soundcore Motion Boom Plus or Soundcore Rave Neo (Trance Go) - best Soundcore speaker??
- Alan Ross Reviews: Soundcore Motion Boom Plus vs Harman Kardon Go+ Play 2 mini - party vs HiFi
- Alan Ross Reviews: Tribit Stormbox Blast or Soundcore Motion Boom Plus or W King D10? 🤪
- Alan Ross Reviews: Tribit Stormbox Blast or two Motion Boom Pluses for best cheap boombox?
- Alan Ross Reviews: Soundcore Boom 2 Plus Review - worst boombox speaker under $400?
- DLX Willington: Tough Game! Tribit Stormbox Blast vs Soundcore Motion Boom Plus Binaural sound samples More from DLXWillington →
- Jay’s Straight Up Reviews & More: NEW RELEASE! Soundcore Boom 2 Plus vs Motion Boom Plus🤯Stock EQ, Bass^ Enabled🤜🤛 A Family Feud😆 More from JaysStraightUpReviews →
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