Short answer: the Harman Kardon Onyx Studio 5. It ranks #21 of 75 boombox speakers by sound quality at $499.99; the Diamondboxx M3 ranks #53 and costs $700, so there is not much of a tradeoff to weigh.
What the Harman Kardon Onyx Studio 5 offers: The iconic circular cabinet and integrated handle make it an attractive room-to-room speaker. Reviews praise its generous bass, balanced mids and smooth top end at moderate levels, giving it a warm, relaxed presentation for casual indoor music. Watch for: The large bass boost can mask lower-mid detail and make dense mixes muddy. Battery life is only around eight hours at moderate volume, it is not especially loud, and it has no water resistance for outdoor use.
What the Diamondboxx M3 offers: An unusually compact 5kg high-output boombox, with a claimed 200W RMS Class A/B amplifier, 114dB maximum level, active crossovers and a choice of large battery packs. It has aux input, USB-C power and TWS pairing, while the aluminum heat sink is designed to sustain loud playback without thermal shutdown. Watch for: Despite its output, bass does not reach as deep as the best large portables and can distort when pushed hard. The treble-forward tuning can sound aggressive, there is no app or EQ to correct it, and the lack of a water rating makes it a poor match for poolside or rough-weather use.
Buy the Harman Kardon Onyx Studio 5. It ranks higher for sound quality than the Diamondboxx M3 and costs less, which settles it without a real tradeoff to make.
There is a real battery-life gap here: the Diamondboxx M3 is rated for 40 hours, the Harman Kardon Onyx Studio 5 only 8 hours.
If water resistance matters to you, the Harman Kardon Onyx Studio 5 at IPX7 (brief submersion) holds up far better than the Diamondboxx M3 at no water resistance.
Still deciding? The full Portable Bluetooth rankings cover every ranked option.
Specifications Side By Side
| Harman Kardon Onyx Studio 5 | Diamondboxx M3 | |
|---|---|---|
| Price | $499.99 | $700 |
| Ranked | #21 of 75 in Boombox Size Portable Bluetooth Speakers | #53 of 75 in Boombox Size Portable Bluetooth Speakers |
| Aux Input | Yes | Yes |
| Battery Life | 8 hours (Manufacturer specified) | 40 hours (Manufacturer specified) |
| IP Rating | IPX7 | None |
| Party Mode | Yes (Wireless Dual Sound) | No |
| Power Input | DC Barrel Connector (19V/2.1A) | USB-C |
| Stereo | Partially (1 woofer) | Yes |
| Omnidirectional | No | No |
| TWS | Yes (see https://www.reddit.com/r/Bluetooth_Speakers/comments/w339x5/how_to_harman_kardon_onyx_studio_5_6_dual_sound/) | Yes |
| Weight | 6.6 lbs (3 kg) | 11 lbs (5 kg) |
| Bluetooth Codecs | SBC | SBC |
| App | No | No |
| EQ | No | No |
| Power Bank | No | No |
| USB Playback | No | No |
| Built-in Microphone | Yes | No |
| Amplifier Power | 50W | 200W RMS / 400W peak |
| Dimensions | 11.3" x 11.3" (285.8 x 285.8 mm) | 14.7" x 9" x 8" (373.4 x 228.6 x 203.2 mm) |
| Drivers | 2x 75mm woofers + 2x 20mm tweeters | 3" woofer + tweeter array |
| Digital Aux Input | No | No |
| FM Tuner | - | No |
Related Speaker Comparisons
More top alternatives to Harman Kardon Onyx Studio 5:
- Tribit Stormbox Blast vs Harman Kardon Onyx Studio 5
- Harman Kardon Go + Play 3 vs Harman Kardon Onyx Studio 5
- JBL Partybox Encore 2 vs Harman Kardon Onyx Studio 5
- JBL Partybox Encore Essential 2 vs Harman Kardon Onyx Studio 5
- JBL Partybox Encore vs Harman Kardon Onyx Studio 5
Prices on this page were last checked September 16, 2026 at 12:41 AM 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 5: $499.99 Amazon eBay
Pros: The iconic circular cabinet and integrated handle make it an attractive room-to-room speaker. Reviews praise its generous bass, balanced mids and smooth top end at moderate levels, giving it a warm, relaxed presentation for casual indoor music.
Cons: The large bass boost can mask lower-mid detail and make dense mixes muddy. Battery life is only around eight hours at moderate volume, it is not especially loud, and it has no water resistance for outdoor use.
Full Harman Kardon Onyx Studio 5 review and specifications →
| Amplifier Power | 50W |
|---|---|
| App | No |
| Aux Input | Yes |
| Battery Life | 8 hours (Manufacturer specified) |
| Bluetooth Codecs | SBC |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 11.3" x 11.3" (285.8 x 285.8 mm) |
| Drivers | 2x 75mm woofers + 2x 20mm tweeters |
| EQ | No |
| IP Rating | IPX7 |
| Omnidirectional | No |
| Party Mode | Yes (Wireless Dual Sound) |
| Power Bank | No |
| Power Input | DC Barrel Connector (19V/2.1A) |
| Stereo | Partially (1 woofer) |
| TWS | Yes (see https://www.reddit.com/r/Bluetooth_Speakers/comments/w339x5/how_to_harman_kardon_onyx_studio_5_6_dual_sound/) |
| USB Playback | No |
| Weight | 6.6 lbs (3 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Harman Kardon Onyx Studio 5 vs JBL Boombox 3 Wifi
- Harman Kardon Onyx Studio 5 vs Harman Kardon Go + Play 2
- Harman Kardon Onyx Studio 5 vs JBL Boombox 4
- Harman Kardon Onyx Studio 5 vs JBL Boombox 3
- Harman Kardon Onyx Studio 5 vs Tribit Stormbox Blast 2
- Harman Kardon Onyx Studio 5 vs Zealot S89
- Harman Kardon Onyx Studio 5 vs LG Xboom Stage 301
- Harman Kardon Onyx Studio 5 vs Zealot ZE21
- See all 58 comparisons
Diamondboxx M3: $700 eBay
Pros: An unusually compact 5kg high-output boombox, with a claimed 200W RMS Class A/B amplifier, 114dB maximum level, active crossovers and a choice of large battery packs. It has aux input, USB-C power and TWS pairing, while the aluminum heat sink is designed to sustain loud playback without thermal shutdown.
Cons: Despite its output, bass does not reach as deep as the best large portables and can distort when pushed hard. The treble-forward tuning can sound aggressive, there is no app or EQ to correct it, and the lack of a water rating makes it a poor match for poolside or rough-weather use.
Full Diamondboxx M3 review and specifications →
| Amplifier Power | 200W RMS / 400W peak |
|---|---|
| App | No |
| Aux Input | Yes |
| Battery Life | 40 hours (Manufacturer specified) |
| Bluetooth Codecs | SBC |
| Built-in Microphone | No |
| Digital Aux Input | No |
| Dimensions | 14.7" x 9" x 8" (373.4 x 228.6 x 203.2 mm) |
| Drivers | 3" woofer + tweeter array |
| EQ | No |
| FM Tuner | No |
| IP Rating | None |
| Omnidirectional | No |
| Party Mode | No |
| Power Bank | No |
| Power Input | USB-C |
| Stereo | Yes |
| TWS | Yes |
| USB Playback | No |
| Weight | 11 lbs (5 kg) |
- Reviews, Comparisons and Sound Samples
- No independent measurement review is linked for this model; it is ranked from hands-on listening and comparison against similarly priced speakers.
- Head-to-Head Comparisons
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