Short answer: the Harman Kardon Onyx Studio 9. It ranks #15 of 98 boombox speakers by sound quality, rated 4.1/5, at $189.99. The Zealot S78 ranks #97, rated 2.0/5, at $159.68, $30.31 cheaper, which does not close the gap in sound quality.
The Harman Kardon Onyx Studio 9 is the better-sounding option. An elegant 9.3 lbs (4.2 kg) living-room portable with a measured 41Hz -10dB bass point, 101dB maximum level, three tweeters, app EQ, stereo pairing and Auracast multi-speaker linking. It links with other speakers (Auracast), which the Zealot S78 cannot. Watch for: It has no water resistance, aux input or USB playback, and its eight-hour claimed battery life is short for an outdoor portable.
The Zealot S78 is the longer-running, tougher pick. A robust 9.7 lbs (4.4 kg) party speaker with claimed 120W RMS output, IP67 protection, USB-C charging, a power-bank function, aux, USB and microSD playback, TWS pairing and multiple EQ modes. It is rated for 40 hours of battery against 8 for the Harman Kardon Onyx Studio 9. It is rated IP67, 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. Watch for: At high volume, reviews report distortion and fluctuating level, so its headline power is more useful below its maximum setting.
Buy the Harman Kardon Onyx Studio 9. It is rated higher for sound quality, and saving $30.31 with the Zealot S78 does not make up for the sound-quality gap.
Want more options? Browse the full Portable Bluetooth rankings.
Specifications Side By Side
| Harman Kardon Onyx Studio 9 | Zealot S78 | |
|---|---|---|
| Price | $189.99 | $159.68 |
| Ranked | #15 of 98 in Boombox Size Portable Bluetooth Speakers | #97 of 98 in Boombox Size Portable Bluetooth Speakers |
| Bass Extension (-10dB) | 41Hz | - |
| Maximum SPL | 101dB (measured by Alan Ross Reviews) | - |
| IP Rating | None | IP67 |
| 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) | 9.7 lbs (4.4 kg) |
| App | Yes (Harman Kardon One app) | No |
| Bluetooth | Yes | Yes |
| Bluetooth Codecs | SBC | SBC |
| EQ | Yes (App EQ) | Yes (multiple modes) |
| Party Mode | Yes (Auracast) | No |
| USB Playback | No | Yes |
| Bluetooth Version | 5.3 | 5.3 |
| Battery Life | 8 hours (Manufacturer specified) | 40 hours (Manufacturer specified) |
| Amplifier Power | 50W RMS | 120W RMS / 150W peak |
| Dimensions | 11.4” x 11.3” x 5.1” (289.2 x 287.5 x 130 mm) | 16.1” x 6.6” x 7.3” (410 x 167 x 185 mm) |
| Drivers | 120mm woofer + 3x 20mm tweeters | 2x ~120mm (4.72”) woofers + 2x ~42mm tweeters + 2x passive radiators |
| Digital Aux Input | No | No |
| Aux Input | No | Yes |
| Strap | No | Yes (detachable shoulder strap) |
| MicroSD Playback | - | Yes |
| Power Bank | - | Yes (USB-A) |
| Built-in Microphone | - | 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 October 12, 2026 at 4:13 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 $189.99 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). See every Harman Kardon Onyx Studio generation.
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 →
| Released | Dec 2024 (1 year ago) |
|---|---|
| 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
- Harman Kardon Onyx Studio 9 vs Harman Kardon Onyx Studio 7
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- Harman Kardon Onyx Studio 9 vs Harman Kardon Onyx Studio 6
- Harman Kardon Onyx Studio 9 vs Zealot ZE21
- Harman Kardon Onyx Studio 9 vs Harman Kardon Onyx Studio 8
- Harman Kardon Onyx Studio 9 vs Zealot S89
- Harman Kardon Onyx Studio 9 vs Yeahbox Sonic Boom Ultra
- See all 99 comparisons
Zealot S78: $159.68 Amazon $159.68 AliExpress $91.38 eBay
Pros: A robust 4.4kg party speaker with claimed 120W RMS output, IP67 protection, USB-C charging, a power-bank function, aux, USB and microSD playback, TWS pairing and multiple EQ modes. Reviews find it very loud with useful bass and long claimed battery life, making it a credible choice for outdoor gatherings.
Cons: At high volume, reviews report distortion and fluctuating level, so its headline power is more useful below its maximum setting. It has no app-based EQ, and the bass and midrange refinement do not match better-established boombox speakers; assess its sound in person if tonal accuracy matters.
Full Zealot S78 review and specifications →
| Released | May 2023 (3 years ago) |
|---|---|
| Amplifier Power | 120W RMS / 150W peak |
| App | No |
| Aux Input | Yes |
| Battery Life | 40 hours (Manufacturer specified) |
| Bluetooth | Yes |
| Bluetooth Codecs | SBC |
| Bluetooth Version | 5.3 |
| Built-in Microphone | No |
| Digital Aux Input | No |
| Dimensions | 16.1” x 6.6” x 7.3” (410 x 167 x 185 mm) |
| Drivers | 2x ~120mm (4.72”) woofers + 2x ~42mm tweeters + 2x passive radiators |
| EQ | Yes (multiple modes) |
| IP Rating | IP67 |
| MicroSD Playback | Yes |
| Omnidirectional | No |
| Party Mode | No |
| Power Bank | Yes (USB-A) |
| Power Input | USB-C |
| Stereo | Yes |
| Strap | Yes (detachable shoulder strap) |
| TWS | Yes |
| USB Playback | Yes |
| Weight | 9.7 lbs (4.4 kg) |
- Links
- Reviews, Comparisons and Sound Samples
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