These speakers often share a shopping shortlist, but they suit different routines. Aura Studio 4 needs a permanent spot near a socket. Onyx Studio 9 and Go + Play 3 can move between rooms without a power cable. The useful differences go beyond the wattage figure.
Harman Kardon ONYX STUDIO 9
Harman/Kardon Aura Studio 4
Harman/Kardon Go+Play3
Comparison and checks
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| Feature | Onyx Studio 9 | Aura Studio 4 | Go + Play 3 |
|---|---|---|---|
| Power | Mains + battery | Mains only | Mains + battery |
| Battery playback* | Up to 8 hours | — | Up to 8 hours |
| Manufacturer-rated power | 50 W RMS | 130 W RMS (2 × 15 + 100) | 160 W RMS |
| Dimensions W × H × D | 289,2 × 287,5 × 130 mm | 232 × 283,6 × 232 mm | 439 × 240 × 192 mm |
| Bluetooth | 5.3 | 4.2 | 5.2 |
| App | Harman Kardon One | Not specified | Not specified |
| Speaker linking | Two Onyx 9s in stereo; compatible speakers via Auracast | Not specified | Two Go + Play 3s |
| Self-tuning at power-on | Yes | Not specified | Yes |
Start with the socket and shelf, not the watts
Aura Studio 4 has no battery operation. It suits a sideboard or stable table where its cable will not get in the way. If you move music to the kitchen in the morning and another room later, Onyx Studio 9 or Go + Play 3 fits that routine better.
Measure the supporting surface. Go + Play 3 is 439 mm wide; Aura is 232 mm deep. Leave access to controls and sockets rather than wedging the body between objects. A battery makes a speaker movable at home, not automatically suitable for outdoor adventures.
Onyx Studio 9: control and room to expand
A practical reason to choose Onyx Studio 9 is Harman Kardon One, with EQ and compatible-speaker control. Power-on self-tuning responds to its surroundings. That helps when moving it, but does not replace careful placement: try another position first if bass seems excessive.
The manufacturer describes stereo pairing with two Onyx Studio 9 speakers. Auracast can also link compatible speakers, but ordinary Bluetooth support does not establish compatibility. Do not buy different models expecting left and right channels without confirming that exact mode.
Aura Studio 4: music and lighting in a permanent spot
The transparent dome and five lighting themes give Aura a clear role as part of a room. Volume is not the only consideration: think about the lighting at night, control access and the route of the power cable.
Do not transfer features from newer Aura models or Onyx to Aura Studio 4. Its documentation does not specify Harman Kardon One support or stereo pairing between two units. If app control and system expansion matter, start with Onyx Studio 9.
Go + Play 3: a larger body and wired sources
Go + Play 3 has a three-way design, a 3.5 mm input and pairing between two Go + Play 3 units. That makes it worth considering for a home source with analogue output. Check the cable and signal type before buying.
USB needs a separate check because the specification distinguishes regional versions. USB file playback is listed for the US version; other versions list USB for service, alongside mobile-device charging. A matching connector does not establish USB audio from your laptop.
Why 160 watts does not mean three times better
The 50, 130 and 160 watt figures describe different designs. They do not calculate sound quality or establish an exact room-size rating. Placement, listening distance and your normal volume all matter.
For a useful comparison, play a familiar recording, match the perceived volume and assess vocals at your normal level. Then try a denser passage. This guide uses documentation; it does not name a bass or detail winner without comparative listening.
Make the decision before buying
Write down three requirements: battery operation, a wired input and a future second speaker. If you do not need a battery and like the dome lighting, Aura is logical. For app control and expansion, look at Onyx 9. For analogue sources and a pair of matching larger units, consider Go + Play 3.
The eight-hour figures are manufacturer maximums dependent on volume and content. Leave a margin for long sessions away from a socket. Check prices, colours and availability below; a permanent best-value ranking quickly becomes outdated.
Frequently asked questions
Can Onyx 9 and Go + Play 3 make a stereo pair?
That mode is not specified. Documentation describes two Onyx 9s or two Go + Play 3s. Auracast on Onyx does not add the feature to the other speaker.
Does Aura Studio 4 work away from a socket?
No. It needs mains power.
Which can replace a TV soundbar?
Do not treat these as direct replacements for an HDMI ARC/eARC soundbar. Check your TV output, delay and volume control separately; see our soundbar guide for that use.
Models at WaveSound
Check the selected product page for current price, availability and package contents.
- Harman Kardon ONYX STUDIO 9 — Price, options and specifications
- Harman/Kardon Aura Studio 4 — Price, options and specifications
- Harman/Kardon Go+Play3 — Price, options and specifications
Related guides
- Soundbar or Stereo Pair for Your Living Room?
- How to connect a soundbar to your TV: HDMI ARC, eARC and optical
Sources and methodology
Prepared by the WaveSound editorial team. Specifications checked against manufacturer documentation on 21 October 2026. Practical advice is editorial guidance; no comparative listening test was performed. Follow the manual for your exact equipment model.