JBL Quantum 400  Headphones Review

The JBL Quantum 400 have a distinctly gamer-oriented aesthetic. They look quite similar to the JBL Quantum 800 Wireless, with a customizable RGB lighting scheme when used with a USB connection and ear cups made of glossy plastic, which tends to show fingerprints. That said, their headband design is quite different, with a rubberized logo stamped into the top and audio cables discretely nestled on their inside surface. Overall, they aren't very discrete or casual and look like gaming headphones.

The JBL Quantum 400 are fairly comfortable. They’re quite lightweight and lined with plush faux leather padding, so they shouldn’t be too fatiguing to wear even during long gaming sessions. They also don’t clamp your head very tightly, but they do offer a slightly more secure fit than the similar JBL Quantum 800 Wireless thanks to their revised headband design, so they shouldn’t fall off if you’re using them for their intended purpose.

These headphones have a disappointingly confusing control scheme. They feature infinite scrolling wheels for volume and channel mixing that are quite close to one another and lack any sort of audio or physical feedback, making it quite easy to change a setting while reaching for another function. That said, their boom microphone can be flipped up to mute it, which is quite intuitive.

The JBL Quantum 400 are similar to other gaming headphones in that they aren’t especially portable. While their ear cups do fold flat, they’re still quite bulky, don’t have a detachable boom microphone, and lack any sort of carrying case to protect them if you end up throwing them into your backpack.

The JBL Quantum 400 don't have a carrying case.

The JBL Quantum 400 are mostly made of dense plastic that feels like it can endure a couple of drops and bumps without too much of an issue but doesn't look especially premium. Their headband and ear cups are lined with decently plush faux leather padding, while their hinges feel sturdier than the similar JBL Quantum 800 Wireless.

Their stability is mediocre. They’ll fall off if you move your head too quickly, so they’re clearly not designed as an accessory for high-intensity workouts. If you intend to use them for their intended purpose as gaming headphones and don’t bob around too much, they shouldn’t shift around on your head.

• JBL Quantum 400 headphones
• USB-A to USB-C cable
• 1/8” TRRS cable
• Manuals

They have a somewhat bass-heavy sound profile that some may perceive as being boomy. Mid accuracy, however, is excellent, so in-game dialogue should be easily discernable, even over the heavy thumps of explosions and gunshots. Their very uneven treble might cause more frequencies to come across as alternatively piercing and veiled. Thankfully, you can customize your listening experience in the JBL Quantum Engine via a graphic EQ or with a selection of seven audio presets to better suit your tastes.

Their frequency response consistency is disappointing. While mids tend to be delivered fairly consistently, sounds in the bass and treble range experience significant variation depending on the headphones' fit and positioning. If you wear glasses or have long hair, it might be tricky to achieve a consistent, repeatable listening experience.

Bass accuracy is decent. Aside from a small dip at the very lowest frequencies, bass is overemphasized across the range, which might please gamers who prefer a little more thump and rumble in their favorite first-person shooters or adventure games, but this also creates a little bit of boominess. That said, their bass accuracy is heavily dependent on the headphones' fit and positioning, so your own listening experience could vary significantly, especially if you wear glasses or have long hair.

The JBL Quantum 400 have remarkable mid accuracy. Sounds across the range follow our target curve almost exactly, ensuring clear and present dialogue, vocals, and lead instruments.

The JBL Quantum 400’s treble accuracy is poor. It’s very uneven across the range, muting the finer edges of higher-pitched vocals and instruments while simultaneously causing sibilants to sound overly bright and piercing. With that said, treble accuracy is based heavily on headphone positioning and fit, so your own experience may vary significantly.

Their peaks and dips performance is sub-par. Some peaks in the bass range are responsible for the boominess heard in their sound profile. A much larger dip in the low-treble range veils higher-pitched vocals and instruments while the adjacent peak causes sibilants to sound piercing and overly bright.

The JBL Quantum 400 have good imaging. Their weighted group delay falls well within acceptable limits, ensuring tight bass and transparent treble reproduction. While there's a slight bump above the audibility threshold in the low bass range, it shouldn't be too noticeable. The L/R drivers on our test unit are quite well-matched. The phase mismatch between the L/R drivers on our test unit is also quite low, which is good for object localization and immersion, especially when playing video games or listening to music in a quiet room. These results are only valid for our test unit, and yours may perform differently.

They have a poor passive soundstage, which is normal for closed-back headphones. Sound will be perceived as coming from the inside of your head rather than outside, resulting in a small-seeming listening experience.

They have JBL's Quantum Surround 7.1 and DTS X 2.0 virtual surround sound features. We currently don't test for these features, however, and the headphones score is based on whether or not they have them.

The JBL Quantum 400's weighted harmonic distortion is okay. There's a spike in the low-treble range at a moderate volume, but that shouldn't be too noticeable, and the rest of the range falls within acceptable limits.

This is the configuration we used testing the JBL Quantum 400. Our results are only valid when using these settings.

The JBL Quantum 400 offer disappointing passive noise isolation performance. They block out very little in the bass range, which means you’ll hear quite a bit of rumble from bus and plane engines. In the mid range, which encompasses ambient speech, their performance is similarly disappointing. They do fare better in the high treble range, effectively blocking out high-pitched noises like AC units and sibilants.

The JBL Quantum 400’s leakage performance is decent. Any audio leakage should be lost at the noise floor of a normal office.

The JBL Quantum 400 have a boom microphone that we tested while using the headphones' USB-A to USB-C cable.

The JBL Quantum 400's microphone recording quality is great. While your voice might sound a little thin, it's also clear, detailed, and full-bodied, so you should be easily understood by your teammates on the other end.

Update 04/04/2022: These headphones have been updated to test bench 1.5. In this update, we changed the way we test noise handling. We now use a subjective evaluation of our audio clips. This new method has resulted in different results than what we had reported in our previous test bench. As a result, the scoring of this box has changed, and we have updated our results.

The JBL Quantum 400's microphone noise handling performance is good. The mic can separate your voice from moderate background noise. Speech is clear and distinguishable, even if you're at a loud gaming tournament.

The JBL Quantum 400 don't have any active features and don't need a battery.

The JBL Quantum 400 are compatible with JBL's Quantum Engine software. It provides users with a 10-band graphic EQ, seven audio presets, channel mixing, RGB lighting customization, and microphone volume adjustment and sidetone microphone monitoring.

The JBL Quantum 400 aren't Bluetooth compatible.

The JBL Quantum 400 can't be used wirelessly. If you're looking for a similar option that can be used without an audio cable, consider the JBL Quantum 800 Wireless.

These headphones come with a 1/8" TRRS cable and a 10 ft USB-A to USB-C cable, which is handy for PS4 and PC users who sit a long way from their devices. When using the headphones, we didn't encounter audio skipping with local videos or videos on our website. However, we noticed that the test track in our Reaper software skipped when the headphones were connected. As a result, we used a local version of our test track to test USB latency instead of using YouTube, which could compensate for audio lag. Using these settings, their USB audio latency is somewhat high, so you may notice syncing issues between your audio and visuals if you're streaming video or gaming.

The JBL Quantum 400 offer full audio and microphone compatibility with Xbox One consoles when you plug the 1/8" TRRS cable into their controller. Unfortunately, you won't be able to use their USB cable with the Xbox One.

These headphones don't have a dock.