These sit in different size classes, so this is not a straight ranking comparison. The Bose SoundLink Plus ranks #25 of 120 large speakers by sound quality at $179; the Harman Kardon Onyx Studio 9 ranks #15 of 113 boombox speakers by sound quality at $184.99.
The Bose SoundLink Plus is the longer-running, lighter choice. A waterproof mid size speaker with vibrant sound, booming bass, clean mids, a long battery and premium build. It is rated for 20 hours of battery against 8 for the Harman Kardon Onyx Studio 9. At 3.3 lbs (1.5 kg) it weighs much less than the Harman Kardon Onyx Studio 9 at 9.3 lbs (4.2 kg). It is rated IP67, while the Harman Kardon Onyx Studio 9 has no water resistance. The tradeoff: Boosted thuddy bass, but not as deep as the SoundLink Flex and you should probably just buy one of those instead if you want a Bose.
The case for the Harman Kardon Onyx Studio 9: An elegant living room portable with balanced, smooth, non-fatiguing sound, app EQ, and stereo pairing for music lovers. It has an adjustable EQ, which the Bose SoundLink Plus lacks. 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 Bose SoundLink Plus at $179 for a large speaker, or the Harman Kardon Onyx Studio 9 at $184.99 for a boombox speaker instead.
Looking for alternatives? See the complete 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
| Bose SoundLink Plus | Harman Kardon Onyx Studio 9 | |
|---|---|---|
| Price | $179.00 | $184.99 |
| Ranked | #25 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 |
| Battery Life | 20 hours (Manufacturer specified) | 8 hours (Manufacturer specified) |
| Built-in Microphone | No | - |
| IP Rating | IP67 | None |
| Party Mode | Yes (Bose Party mode) | Yes (Auracast) |
| Power Bank | Yes (USB-C) | - |
| Power Input | USB-C | AC Power Cable (2-Prong) |
| TWS | Yes | Yes |
| Weight | 3.3 lbs (1.5 kg) | 9.3 lbs (4.2 kg) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC |
| EQ | No | Yes (App EQ) |
| Stereo | Yes | Yes |
| Omnidirectional | No | No |
| Bluetooth Version | 5.4 | 5.3 |
| Dimensions | 9.1” x 3.9” x 3.4” (231 x 99 x 86 mm) | 11.4” x 11.3” x 5.1” (289.2 x 287.5 x 130 mm) |
| Drivers | 1x 2.5” (63.5mm) woofer + 1x ~0.78” (20mm) tweeter + 4x passive radiators | 120mm woofer + 3x 20mm tweeters |
| Digital Aux Input | No | No |
| Strap | Yes (built-in loop) | No |
| Bass Extension (-10dB) | - | 41Hz |
| Maximum SPL | - | 101dB (measured by Alan Ross Reviews) |
| USB Playback | - | No |
| Amplifier Power | - | 50W RMS |
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