Short answer: the Harman Kardon Onyx Studio 9. It ranks #15 of 89 boombox speakers by sound quality (rated 4.1/5); the Teufel Boomster 4 ranks #44 (rated 3.4/5).
Why pick the Harman Kardon Onyx Studio 9: 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. 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.
Why pick the Teufel Boomster 4: Warmer and more open than the Boomster 2021 it replaces, with nicer, less harsh highs, a wide stereo image from its three-way layout (two 20mm tweeters, two 65mm midrange drivers and a 110mm woofer with passive radiators) and good detail. The catch: Side by side with the Boomster 2021 the sound barely changed, and it has a little less deep bass.
Buy the Harman Kardon Onyx Studio 9. It is rated higher for sound quality than the Teufel Boomster 4.
Water resistance is not close: the Teufel Boomster 4 is rated at IPX5 (water jets), well ahead of the Harman Kardon Onyx Studio 9 at no water resistance.
Still deciding? The full Portable Bluetooth rankings cover every ranked option.
Specifications Side By Side
| Harman Kardon Onyx Studio 9 | Teufel Boomster 4 | |
|---|---|---|
| Price | $189.99 | €249.99 |
| Ranked | #15 of 89 in Boombox Size Portable Bluetooth Speakers | #44 of 89 in Boombox Size Portable Bluetooth Speakers |
| Bass Extension (-10dB) | 41Hz | - |
| Maximum SPL | 101dB (measured by Alan Ross Reviews) | - |
| IP Rating | None | IPX5 |
| 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) | 8.3 lbs (3.75 kg) |
| App | Yes (Harman Kardon One app) | No |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | aptX HD, AAC, SBC |
| EQ | Yes (App EQ) | Yes (treble control) |
| Party Mode | Yes (Auracast) | - |
| USB Playback | No | - |
| Bluetooth Version | 5.3 | 5.0 |
| Battery Life | 8 hours (Manufacturer specified) | 23 hours (Manufacturer specified) |
| Amplifier Power | 50W RMS | 42W RMS |
| Dimensions | 11.4” x 11.3” x 5.1” (289.2 x 287.5 x 130 mm) | 7.1”H x 14.6”W x 5.8”D (180 x 370 x 148 mm) |
| Drivers | 120mm woofer + 3x 20mm tweeters | 2x 20mm tweeters + 2x 65mm midrange drivers + 1x 110mm (4.3”) woofer, passive bass radiators |
| Digital Aux Input | No | - |
| Aux Input | No | Yes |
| Strap | No | No |
| FM Tuner | - | Yes (plus DAB+) |
| Power Bank | - | No |
Related Speaker Comparisons
More worthwhile head-to-heads for Harman Kardon Onyx Studio 9:
- 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 September 30, 2026 at 2:57 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 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).
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 →
| 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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Teufel Boomster 4: €249.99 Teufel eBay
Older models: the Teufel Boomster 2021 (ranked lower, rated 3.4/5) and the Teufel Boomster NG (2017) (ranked lower, rated 3.2/5).
Pros: Warmer and more open than the Boomster 2021 it replaces, with nicer, less harsh highs, a wide stereo image from its three-way layout (two 20mm tweeters, two 65mm midrange drivers and a 110mm woofer with passive radiators) and good detail. Its new treble control and remote let you tame the top end. DAB+ and FM radio, a claimed 23 hours of battery at medium volume, IPX5, Bluetooth 5.0 with AAC and aptX HD, multipoint, an aux input, USB-C charging and stereo pairing.
Cons: Side by side with the Boomster 2021 the sound barely changed, and it has a little less deep bass. Against the Harman Kardon Go + Play 3 it sounds sharper and thinner, with weaker bass and a less natural stereo image, and its bass drops off at full volume. At 3.75 kg it is heavy for its size, it has no power bank output, and IPX5 is a step down from the older model’s IPX7.
Full Teufel Boomster 4 review and specifications →
| Amplifier Power | 42W RMS |
|---|---|
| App | No |
| Aux Input | Yes |
| Battery Life | 23 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | aptX HD, AAC, SBC |
| Bluetooth Version | 5.0 |
| Dimensions | 7.1”H x 14.6”W x 5.8”D (180 x 370 x 148 mm) |
| Drivers | 2x 20mm tweeters + 2x 65mm midrange drivers + 1x 110mm (4.3”) woofer, passive bass radiators |
| EQ | Yes (treble control) |
| FM Tuner | Yes (plus DAB+) |
| IP Rating | IPX5 |
| Omnidirectional | No |
| Power Bank | No |
| Power Input | USB-C |
| Stereo | Yes |
| Strap | No |
| TWS | Yes |
| Weight | 8.3 lbs (3.75 kg) |
- Links
- Reviews, Comparisons and Sound Samples
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