Short answer: the Yeahbox Sonic Boom Ultra. It ranks #11 of 112 boombox speakers by sound quality (rated 4.2/5) at $388 and is still sold new; the Harman Kardon Onyx Studio 8 ranks #12 (rated 4.1/5) and is discontinued, so it is only an option used. The Harman Kardon Onyx Studio 8’s replacement, the Harman Kardon Onyx Studio 9, is rated 4.1/5 at $184.99.
The Yeahbox Sonic Boom Ultra is the longer-running, tougher choice. A massively loud boombox with deep bass, long battery life, and HDMI ARC so it can double as a TV soundbar. It is rated for 24 hours of battery against 8 for the Harman Kardon Onyx Studio 8. It is rated IPX6, while the Harman Kardon Onyx Studio 8 has no water resistance. The tradeoff: The 500W peak-power rating doesn’t fully hold up: it gets noisy above roughly 80-90% volume, and the midrange isn’t fully refined, sometimes sitting a touch too forward.
The Harman Kardon Onyx Studio 8 is the lighter pick. A stylish room-to-room speaker with warm, full sound, deep bass, and app EQ in a light, easy to carry body. At 7.3 lbs (3.3 kg) it weighs much less than the Yeahbox Sonic Boom Ultra at 24.3 lbs (11 kg). The catch: Warm tuning with boosted bass, not as loud as others, and no water resistance rating.
Buy the Yeahbox Sonic Boom Ultra. It is rated higher for sound quality; the Harman Kardon Onyx Studio 8 is no longer sold new.
Want more options? Browse the full Portable Bluetooth rankings.
A massively loud boombox with deep bass, long battery life, and HDMI ARC so it can double as a TV soundbar.
A stylish room-to-room speaker with warm, full sound, deep bass, and app EQ in a light, easy to carry body.
Prices on this page were last checked October 31, 2026 at 7:11 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
| Yeahbox Sonic Boom Ultra | Harman Kardon Onyx Studio 8 | |
|---|---|---|
| Price | $388.00 | $199.00 Discontinued |
| Ranked | #11 of 112 in Boombox Size Portable Bluetooth Speakers | #12 of 112 in Boombox Size Portable Bluetooth Speakers |
| App | Yes | Yes (Harman Kardon One app) |
| Aux Input | Yes | Yes |
| Battery Capacity | 45000mAh (Reviewer estimated) | - |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 6.0 | 5.2 |
| Dimensions | 23.4” x 9.8” x 12.3” (595 x 248 x 313 mm) | 10.6” x 11.9” x 6.3” (268 x 302.5 x 159.5 mm) |
| Drivers | 6x9in racetrack woofer (200W) + 2x 4.5in midrange (40W each) + 2x tweeters (20W each), true 3-way | 120mm woofer + 2x 20mm tweeters |
| EQ | Yes (Country, Classic, and custom app EQ; custom settings don’t persist after the app closes) | Yes (App EQ) |
| Inputs | HDMI ARC (in/out, usable as a TV soundbar), AUX in/out, USB drive, microSD, optional wired mic | - |
| IP Rating | IPX6 | None |
| MicroSD Playback | Yes | - |
| Amplifier Power | 320W RMS / 500W Peak | 50W RMS |
| Party Mode | No (TWS stereo pairing of 2 units only, no Auracast) | No |
| Power Input | USB-C (60W fast charging) | DC Barrel Connector (19V/2.1A) |
| Stereo | Yes | Partially (1 woofer) |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| USB Playback | Yes | No |
| Weight | 24.3 lbs (11 kg) | 7.3 lbs (3.3 kg) |
| Digital Aux Input | No | No |
| Bluetooth Codecs | SBC (inferred; additional codecs unverified) | SBC |
| Lights | Yes | - |
| Battery Life | 24 hours (Manufacturer specified) | 8 hours (Manufacturer specified) |
| Strap | No | No |
| Aux Latency | - | 42ms |
| Bass Extension (-10dB) | - | 35Hz |
| Built-in Microphone | - | Yes |
| Bluetooth Latency | - | 175ms |
| Maximum SPL | - | 96dB (measured by Alan Ross Reviews) |
| Power Bank | - | No |
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