Short answer: the Harman Kardon Onyx Studio 9. It ranks #15 of 113 boombox speakers by sound quality (rated 4.1/5); the Teufel Boomster 4 ranks #50 (rated 3.4/5).
The Harman Kardon Onyx Studio 9 is the better-sounding option. An elegant living room portable with balanced, smooth, non-fatiguing sound, app EQ, and stereo pairing for music lovers. 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 Teufel Boomster 4 is the longer-running, tougher pick. A stereo boombox with DAB+ and FM radio, a long battery, splash resistance and a remote with treble control. It is rated for 23 hours of battery against 8 for the Harman Kardon Onyx Studio 9. It is rated IPX5, while the Harman Kardon Onyx Studio 9 has no water resistance. It supports aptX HD Bluetooth, which the Harman Kardon Onyx Studio 9 lacks. The tradeoff: Side by side with the Teufel 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.
Still deciding? The full Portable Bluetooth rankings cover every ranked option.
Prices on this page were last checked November 14, 2026 at 6:17 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 | Teufel Boomster 4 | |
|---|---|---|
| Price | $184.99 | €249.99 |
| Ranked | #15 of 113 in Boombox Size Portable Bluetooth Speakers | #50 of 113 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 |
Where the Ratings Come From
- Harman Kardon Onyx Studio 9: reviews by Alan Ross.
- Teufel Boomster 4: reviews by Dominik and Mateusz Cholewa.
This comparison is generated from the ratings, specifications and measurements on each product’s own page, and it updates when that data changes. How we rank explains how each rating is decided.
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