Harman Kardon Onyx Studio 9 vs Soundcore Motion Boom+

Last updated: August 28, 2026

Short answer: the Harman Kardon Onyx Studio 9 on measured sound quality, the Soundcore Motion Boom+ on price. The Harman Kardon Onyx Studio 9 ranks #13 of 73 boombox speakers at $186.99. The Soundcore Motion Boom+ ranks #47 at $140, $46.99 cheaper.

What the Harman Kardon Onyx Studio 9 offers: Auracast multi-speaker connection alongside classic stereo pairing. Harman Kardon One app with EQ. USB-C charging, up from the previous generation’s AC power brick. Watch for: Slight recessed mids, boost in the upper mids, rolled off upper treble. Not as deep bass as previous Onyx Studio speakers.

What the Soundcore Motion Boom+ offers: 80W stereo from dual 30W woofers + dual 10W tweeters with titanium drivers for treble clarity. 13,400mAh battery for 20 hours (12-15 at high volume). IP67 waterproof, floats, rugged build inspires confidence. Bluetooth 5.3 multipoint pairing, Soundcore app EQ, PartyCast 2.0 mode. USB-C input, USB-A output for powerbank. Watch for: Default presets are all warm sounding with rolled off treble. Will need a custom EQ to get closer to neutral. A shrill sounding 6khz peak comes out when volume is above about 60%. Not much deeper bass than a Motion Boom and a lot less deep bass than other speakers in the class.

Buy the Harman Kardon Onyx Studio 9 if sound quality matters more than the price. Buy the Soundcore Motion Boom+ if the price matters more than sound quality.

If battery life is a priority, the Soundcore Motion Boom+ is rated for 20 hours versus 8 hours for the Harman Kardon Onyx Studio 9.

There is a real gap in water resistance: the Soundcore Motion Boom+ at IP67 (brief submersion) against the Harman Kardon Onyx Studio 9, which has no water resistance.

Buy the Harman Kardon Onyx Studio 9 at Amazon ($186.99) →Buy the Soundcore Motion Boom+ at Amazon ($140) →

Harman Kardon Onyx Studio 9 vs Soundcore Motion Boom+

Specifications Side By Side

Harman Kardon Onyx Studio 9 Soundcore Motion Boom+
Price$186.99$140 after $40 coupon, Discontinued
Ranked#13 of 73 in Boombox Size Portable Bluetooth Speakers#47 of 73 in Boombox Size Portable Bluetooth Speakers
Bass Extension (-10dB)41Hz52Hz
Max Volume101dB108dB
IP RatingNoneIP67
Power InputAC Power Cable (2-Prong)USB-C
StereoYesYes
OmnidirectionalNoNo
TWSYesYes
Weight9.3 lbs / 4.2 kg5.3 lbs / 2.4 kg
AppYes (Harman Kardon One app)Yes (Soundcore app)
Bluetooth CodecsSBCSBC
EQYes (App EQ)Yes (App EQ)
Party ModeYes (Auracast)Yes (PartyCast up to 100 speakers)
USB PlaybackNoNo
Bluetooth Version5.35.3
Battery Life8 hours (Manufacturer specified)20 hours (Manufacturer specified)
Output Power50W RMS80W
Dimensions11.4" x 11.3" x 5.1" (289.2 x 287.5 x 130 mm)15.1" x 5.1" x 7.7" (384 x 130 x 196 mm)
Drivers120mm woofer + 3x 20mm tweeters30W: Dual drivers
Digital Aux InputNoNo
Aux Input-Yes
Aux Latency-17ms
Bluetooth Latency-33ms
Power Bank-Yes (USB-A, 5V/2.1A)
Built in Microphone-No
Discontinued-Yes
Buy the Harman Kardon Onyx Studio 9 at Amazon ($186.99) →Buy the Soundcore Motion Boom+ at Amazon ($140) →

Other pairings from the same speaker class worth checking:

Prices on this page were last checked August 27, 2026 at 10:09 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: $186.99 Amazon eBay

Harman Kardon Onyx Studio 9 ranking card

Pros: Auracast multi-speaker connection alongside classic stereo pairing. Harman Kardon One app with EQ. USB-C charging, up from the previous generation’s AC power brick.

Cons: Slight recessed mids, boost in the upper mids, rolled off upper treble. Not as deep bass as previous Onyx Studio speakers.

Full Harman Kardon Onyx Studio 9 review and specifications →

AppYes (Harman Kardon One app)
Bass Extension (-10dB)41Hz
Battery Life8 hours (Manufacturer specified)
Bluetooth CodecsSBC
Bluetooth Version5.3
Digital Aux InputNo
Dimensions11.4" x 11.3" x 5.1" (289.2 x 287.5 x 130 mm)
Drivers120mm woofer + 3x 20mm tweeters
EQYes (App EQ)
IP RatingNone
Max Volume101dB
OmnidirectionalNo
Output Power50W RMS
Party ModeYes (Auracast)
Power InputAC Power Cable (2-Prong)
StereoYes
TWSYes
USB PlaybackNo
Weight9.3 lbs / 4.2 kg
Check current price at Amazon ($186.99) →Search eBay for Harman Kardon Onyx Studio 9 →

Soundcore Motion Boom+: $140 after $40 coupon, Discontinued Amazon eBay

Soundcore Motion Boom+ ranking card

Pros: 80W stereo from dual 30W woofers + dual 10W tweeters with titanium drivers for treble clarity. 13,400mAh battery for 20 hours (12-15 at high volume). IP67 waterproof, floats, rugged build inspires confidence. Bluetooth 5.3 multipoint pairing, Soundcore app EQ, PartyCast 2.0 mode. USB-C input, USB-A output for powerbank.

Cons: Default presets are all warm sounding with rolled off treble. Will need a custom EQ to get closer to neutral. A shrill sounding 6khz peak comes out when volume is above about 60%. Not much deeper bass than a Motion Boom and a lot less deep bass than other speakers in the class. Discontinued.

Full Soundcore Motion Boom+ review and specifications →

AppYes (Soundcore app)
Aux InputYes
Aux Latency17ms
Bass Extension (-10dB)52Hz
Battery Life20 hours (Manufacturer specified)
Bluetooth CodecsSBC
Bluetooth Latency33ms
Bluetooth Version5.3
Built in MicrophoneNo
Digital Aux InputNo
Dimensions15.1" x 5.1" x 7.7" (384 x 130 x 196 mm)
DiscontinuedYes
Drivers30W: Dual drivers
EQYes (App EQ)
IP RatingIP67
Max Volume108dB
OmnidirectionalNo
Output Power80W
Party ModeYes (PartyCast up to 100 speakers)
Power BankYes (USB-A, 5V/2.1A)
Power InputUSB-C
StereoYes
TWSYes
USB PlaybackNo
Weight5.3 lbs / 2.4 kg
Check current price at Amazon ($140) →Search eBay for Soundcore Motion Boom+ →