Harman Kardon Onyx Studio 7 vs Diamondboxx M3

Last updated: September 16, 2026

Short answer: the Harman Kardon Onyx Studio 7. It ranks #13 of 75 boombox speakers by sound quality at $248.90; the Diamondboxx M3 ranks #53 and costs $700, which makes this an easy call rather than a real tradeoff.

Harman Kardon Onyx Studio 7 vs Diamondboxx M3

What the Harman Kardon Onyx Studio 7 offers: The addition of dual tweeters gives the Studio 7 a wider, more spacious presentation than older Onyx models. It delivers strong, deep bass, useful large-room volume and can pair with a second Studio 7 for stereo. Watch for: Consumer Reports finds the bass prominent and boomy, mids hazy, treble slightly smeared and the soundstage congested. Battery life remains only about eight hours, it has no water rating or advanced codecs, and it is not an especially loud outdoor speaker.

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 7. It ranks higher for sound quality than the Diamondboxx M3 and costs less, so there is no real case for the other one.

There is a real battery-life gap here: the Diamondboxx M3 is rated for 40 hours, the Harman Kardon Onyx Studio 7 only 8 hours.

Still deciding? The full Portable Bluetooth rankings cover every ranked option.

Buy the Harman Kardon Onyx Studio 7 at Amazon ($248.90) →

Specifications Side By Side

Harman Kardon Onyx Studio 7 Diamondboxx M3
Price$248.90$700
Ranked#13 of 75 in Boombox Size Portable Bluetooth Speakers#53 of 75 in Boombox Size Portable Bluetooth Speakers
Aux InputYesYes
Aux Latency0ms-
Bass Extension (-10dB)37Hz-
Battery Life8 hours (Manufacturer specified)40 hours (Manufacturer specified)
Built-in MicrophoneYesNo
IP RatingNoneNone
Bluetooth Latency266ms-
Maximum SPL96dB (measured by Alan Ross Reviews)-
Party ModeYes (Wireless Dual Sound)No
Power InputDC Barrel Connector (19V/2.1A)USB-C
StereoPartially (1 woofer)Yes
OmnidirectionalNoNo
TWSNoYes
Weight6.4 lbs (2.9 kg)11 lbs (5 kg)
Bluetooth CodecsSBCSBC
AppNoNo
EQNoNo
Power BankNoNo
USB PlaybackNoNo
Amplifier Power50W RMS200W RMS / 400W peak
Dimensions11.3" x 11.3" (285.8 x 285.8 mm) (round design)14.7" x 9" x 8" (373.4 x 228.6 x 203.2 mm)
Drivers2x 75mm woofers + 2x 20mm tweeters3" woofer + tweeter array
Digital Aux InputNoNo
FM Tuner-No
Buy the Harman Kardon Onyx Studio 7 at Amazon ($248.90) →

How Harman Kardon Onyx Studio 7 compares with other leading options:

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 7: $248.90 Amazon eBay

Harman Kardon Onyx Studio 7 ranking card

Pros: The addition of dual tweeters gives the Studio 7 a wider, more spacious presentation than older Onyx models. It delivers strong, deep bass, useful large-room volume and can pair with a second Studio 7 for stereo. Measured bass extension of 37Hz (-10dB).

Cons: Consumer Reports finds the bass prominent and boomy, mids hazy, treble slightly smeared and the soundstage congested. Battery life remains only about eight hours, it has no water rating or advanced codecs, and it is not an especially loud outdoor speaker.

Full Harman Kardon Onyx Studio 7 review and specifications →

Amplifier Power50W RMS
AppNo
Aux InputYes
Aux Latency0ms
Bass Extension (-10dB)37Hz
Battery Life8 hours (Manufacturer specified)
Bluetooth CodecsSBC
Bluetooth Latency266ms
Built-in MicrophoneYes
Digital Aux InputNo
Dimensions11.3" x 11.3" (285.8 x 285.8 mm) (round design)
Drivers2x 75mm woofers + 2x 20mm tweeters
EQNo
IP RatingNone
Maximum SPL96dB (measured by Alan Ross Reviews)
OmnidirectionalNo
Party ModeYes (Wireless Dual Sound)
Power BankNo
Power InputDC Barrel Connector (19V/2.1A)
StereoPartially (1 woofer)
TWSNo
USB PlaybackNo
Weight6.4 lbs (2.9 kg)
Check current price at Amazon ($248.90) →Search eBay for Harman Kardon Onyx Studio 7 →

Diamondboxx M3: $700 eBay

Diamondboxx M3 ranking card

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 Power200W RMS / 400W peak
AppNo
Aux InputYes
Battery Life40 hours (Manufacturer specified)
Bluetooth CodecsSBC
Built-in MicrophoneNo
Digital Aux InputNo
Dimensions14.7" x 9" x 8" (373.4 x 228.6 x 203.2 mm)
Drivers3" woofer + tweeter array
EQNo
FM TunerNo
IP RatingNone
OmnidirectionalNo
Party ModeNo
Power BankNo
Power InputUSB-C
StereoYes
TWSYes
USB PlaybackNo
Weight11 lbs (5 kg)
Search eBay for Diamondboxx M3 →