Short answer: the Onyx Studio 9 for balanced sound, the W-King D20 for karaoke. The D20 comes with 2 wireless microphones, but it has a rising frequency response with upper treble rolled off and 700Hz and 1.2kHz peaks. The Onyx Studio 9 adds Auracast multi-speaker connection alongside classic stereo pairing, though it has slightly recessed mids, a boost in the upper mids and rolled off upper treble.
Buy the Harman Kardon Onyx Studio 9. It is rated higher for sound quality than the W-King D20 and costs less, which makes it the one to get unless you need something the other one does better.
There is a real battery-life gap here: the W-King D20 is rated for 24 hours, the Harman Kardon Onyx Studio 9 only 8 hours.
There is a real gap in water resistance: the W-King D20 at IPX6 (powerful water jets) against the Harman Kardon Onyx Studio 9, which has no water resistance.
Want more options? Browse the full Portable Bluetooth rankings.
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Specifications Side By Side
| Harman Kardon Onyx Studio 9 | W-King D20 | |
|---|---|---|
| Price | $184.99 | $193 |
| Ranked | #15 of 113 in Boombox Size Portable Bluetooth Speakers | #41 of 113 in Boombox Size Portable Bluetooth Speakers |
| Bass Extension (-10dB) | 41Hz | ~42Hz |
| Maximum SPL | 101dB (measured by Alan Ross Reviews) | 112dB (measured by Alan Ross Reviews) |
| IP Rating | None | IPX6 |
| 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) | 14.3 lbs (6500 g) |
| App | Yes (Harman Kardon One app) | Yes (W-King app) |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC |
| EQ | Yes (App EQ) | Yes (App + button modes) |
| Party Mode | Yes (Auracast) | No |
| USB Playback | No | Yes |
| Bluetooth Version | 5.3 | 5.3 |
| Battery Life | 8 hours (Manufacturer specified) | 24 hours (Manufacturer specified) |
| Amplifier Power | 50W RMS | 200W |
| Dimensions | 11.4” x 11.3” x 5.1” (289.2 x 287.5 x 130 mm) | 19.9” x 8.5” x 10.6” (506 x 217 x 270 mm) |
| Drivers | 120mm woofer + 3x 20mm tweeters | 4.5” + 3.5” drivers + 1.2” tweeters |
| Digital Aux Input | No | No |
| Aux Input | No | Yes |
| Strap | No | - |
| MicroSD Playback | - | Yes |
| Wireless Microphones | - | Yes |
| Power Bank | - | Yes |
| Built-in Microphone | - | No |
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