Short answer: the Yeahbox Sonic Boom Ultra for better sound quality, the Harman Kardon Onyx Studio 9 for the lower price. The Yeahbox Sonic Boom Ultra ranks #11 of 112 boombox speakers, rated 4.2/5, at $388. The Harman Kardon Onyx Studio 9 ranks #15, rated 4.1/5, at $184.99, $203.01 cheaper.
The Harman Kardon Onyx Studio 9 is the lighter option. An elegant living room portable with balanced, smooth, non-fatiguing sound, app EQ, and stereo pairing for music lovers. At 9.3 lbs (4.2 kg) it weighs much less than the Yeahbox Sonic Boom Ultra at 24.3 lbs (11 kg). It links with other speakers (Auracast), which the Yeahbox Sonic Boom Ultra cannot. The tradeoff: It has no water resistance, aux input or USB playback, and its eight-hour claimed battery life is short for an outdoor portable.
The Yeahbox Sonic Boom Ultra is the longer-running, tougher choice. A massively loud boombox with deep bass, long battery life, and HDMI ARC so it can double as a TV soundbar. It is rated for 24 hours of battery against 8 for the Harman Kardon Onyx Studio 9. It is rated IPX6, while the Harman Kardon Onyx Studio 9 has no water resistance. It keeps a wired aux input, which the Harman Kardon Onyx Studio 9 lacks. The catch: The 500W peak-power rating doesn’t fully hold up: it gets noisy above roughly 80-90% volume, and the midrange isn’t fully refined, sometimes sitting a touch too forward.
Buy the Harman Kardon Onyx Studio 9 if the price is the priority over sound quality, or the Yeahbox Sonic Boom Ultra if sound quality is the priority over the price.
Want more options? Browse the full Portable Bluetooth rankings.
An elegant living room portable with balanced, smooth, non-fatiguing sound, app EQ, and stereo pairing for music lovers.
A massively loud boombox with deep bass, long battery life, and HDMI ARC so it can double as a TV soundbar.
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.
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Specifications Side By Side
| Harman Kardon Onyx Studio 9 | Yeahbox Sonic Boom Ultra | |
|---|---|---|
| Price | $184.99 | $388.00 |
| Ranked | #15 of 112 in Boombox Size Portable Bluetooth Speakers | #11 of 112 in Boombox Size Portable Bluetooth Speakers |
| Bass Extension (-10dB) | 41Hz | - |
| Maximum SPL | 101dB (measured by Alan Ross Reviews) | - |
| IP Rating | None | IPX6 |
| Power Input | AC Power Cable (2-Prong) | USB-C (60W fast charging) |
| Stereo | Yes | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 9.3 lbs (4.2 kg) | 24.3 lbs (11 kg) |
| App | Yes (Harman Kardon One app) | Yes |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC (inferred; additional codecs unverified) |
| EQ | Yes (App EQ) | Yes (Country, Classic, and custom app EQ; custom settings don’t persist after the app closes) |
| Party Mode | Yes (Auracast) | No (TWS stereo pairing of 2 units only, no Auracast) |
| USB Playback | No | Yes |
| Bluetooth Version | 5.3 | 6.0 |
| Battery Life | 8 hours (Manufacturer specified) | 24 hours (Manufacturer specified) |
| Amplifier Power | 50W RMS | 320W RMS / 500W Peak |
| Dimensions | 11.4” x 11.3” x 5.1” (289.2 x 287.5 x 130 mm) | 23.4” x 9.8” x 12.3” (595 x 248 x 313 mm) |
| Drivers | 120mm woofer + 3x 20mm tweeters | 6x9in racetrack woofer (200W) + 2x 4.5in midrange (40W each) + 2x tweeters (20W each), true 3-way |
| Digital Aux Input | No | No |
| Aux Input | No | Yes |
| Strap | No | No |
| Battery Capacity | - | 45000mAh (Reviewer estimated) |
| Inputs | - | HDMI ARC (in/out, usable as a TV soundbar), AUX in/out, USB drive, microSD, optional wired mic |
| MicroSD Playback | - | Yes |
| Lights | - | Yes |
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