Haylou S40 Review: ANC Earbuds With Surprisingly Long Battery Life

Worth clearing up first: the Haylou S40 is a pair of true wireless earbuds, not a smartwatch, despite the model number occasionally getting confused with Haylou’s watch lineup in searches. I tested a pair over two weeks of regular commuting and desk work to see how its noise cancellation and battery claims hold up.

Standout Features

The S40 leans heavily into audio quality claims, including dual Hi-Res certifications and LDAC support at up to 990kbps for 96kHz/24-bit playback when paired with a compatible source. Active noise cancellation is rated up to 50dB, alongside a 360-degree spatial audio mode driven by a 6-axis relative positioning sensor that tracks head movement.

• Titanium drivers tuned for a fuller low end
• Adaptive EQ that adjusts tuning based on ambient noise and fit
• Dual-device Bluetooth connection for switching between a laptop and phone

Battery Life In Practice

Haylou’s claimed figures are genuinely impressive on paper — around 90 hours total playback with ANC off at moderate volume, and roughly 60 hours with ANC on. In my own testing with ANC on for most sessions, real-world battery life ran a bit under the official claim but still comfortably outlasted several other budget ANC earbuds I have used previously.

Noise Cancellation And Spatial Audio

The ANC performance on continuous noise (fans, engine hum, air conditioning) was solid and comparable to the FlowBuds N55, which makes sense given both target a similar ANC tier within Haylou’s catalog. The 360-degree spatial audio mode is a genuinely interesting extra — turning your head shifts the perceived sound direction in supported content, though the effect is subtle rather than dramatic on regular stereo music.

Everyday Usability

1. Dual-device connection made switching between a work laptop and phone seamless without manual re-pairing
2. Adaptive EQ noticeably adjusted tuning when I moved from a quiet room to a noisy street
3. Touch controls responded consistently without accidental triggers during workouts

Full specifications and current pricing are listed on the official Haylou S40 product page, which is worth checking directly since regional pricing and bundled accessories can vary.

Comfort And Fit Over Long Sessions

The S40’s shell sits relatively shallow in the ear, which helped avoid the pressure discomfort I sometimes get from deeper-fitting ANC earbuds during multi-hour work sessions. Three included tip sizes covered a good range of ear shapes, and I did not experience any looseness or accidental disconnects during light exercise.

Setting Up LDAC And Adaptive EQ

1. Pair the S40 with your phone through standard Bluetooth settings
2. If your phone supports LDAC, enable it manually in your device’s Bluetooth audio codec settings (this is usually under Developer Options on Android)
3. Open the companion app to toggle adaptive EQ and confirm ANC mode preferences
4. Test playback with a familiar track to confirm the codec switch actually applied, since some phones silently fall back to AAC if LDAC is unstable

It is easy to assume LDAC is active just because you enabled it in settings, but checking playback quality directly is the only reliable way to confirm the codec actually stuck for a given listening session.

How The Spatial Audio Mode Actually Feels

Turning the spatial audio feature on inside the companion app noticeably shifted the perceived sound field when I turned my head during a supported video, similar in concept to spatial audio features on more expensive earbuds. On regular stereo music without spatial mixing, the effect is far more subtle and mostly just widens the perceived soundstage slightly rather than creating a dramatic surround effect. I would treat it as a nice bonus for compatible video content rather than a reason to buy the S40 on its own.

Value For Money

• LDAC and dual Hi-Res certification at a price point where both are still relatively rare
• Genuinely long battery life that held up close to Haylou’s claims in daily mixed use
• Spatial audio and adaptive EQ as useful extras rather than gimmicks tacked on for marketing

Taken together, the S40 represents one of the stronger value propositions currently in Haylou’s earbud lineup for anyone prioritizing audio quality and battery life over a compact case size.

Build Quality And Case Design

The S40’s charging case uses a matte finish that resists fingerprints noticeably better than glossy competitors, and the hinge felt solid rather than loose after two weeks of regular opening and closing. USB-C charging on the case itself is standard at this point, but still worth confirming before buying if you are trying to standardize your cables across devices.

Who Should Consider The S40

Anyone prioritizing genuinely long battery life alongside strong audio codec support will find the S40 a compelling budget option. If your priority instead leans toward gaming latency or an open-ear design, Haylou’s HQ3 or OW03 respectively are better suited to those specific needs.

Packaging And First Impressions

The retail box includes the earbuds, case, a short USB-C cable, three ear tip sizes, and a printed quick-start guide, which is a fairly standard inclusion list at this price point. Nothing about the unboxing experience feels premium, but everything needed to get started is present without hunting for missing accessories.

Troubleshooting Common S40 Problems

Most of the issues I ran into (or heard about from other owners) came down to a handful of repeat offenders, so here is what to check before assuming the earbuds themselves are faulty.

• One earbud will not connect: put both earbuds back in the case, close the lid for about ten seconds, then take them out and let them re-sync with each other before reconnecting to your phone. A single earbud dropping out mid-session is almost always a sync issue between the two buds rather than a hardware fault.
• Stuck in pairing mode or not showing up in Bluetooth settings: forget the S40 from your phone’s Bluetooth list entirely, place both earbuds back in the case, then re-open the lid near your phone to trigger a fresh pairing prompt rather than trying to reconnect to a stale saved connection.
• ANC does not seem to be doing anything: confirm ANC is actually toggled on inside the companion app rather than just the default mode, and check that the ear tip size you are using is sealing properly, since a loose seal lets in ambient noise that ANC cannot fully cancel out.
• Touch controls stop responding: a bit of ear wax or moisture on the touch sensor is the most common cause, so wipe the outer surface of each earbud dry before assuming a defect.
• Firmware update fails or gets stuck: keep both earbuds in the case with the lid open and your phone nearby for the full update, since a closed lid or a dropped Bluetooth connection partway through is the usual reason an update stalls or fails to complete.

Frequently Asked Questions

Is the Haylou S40 a smartwatch or earbuds?

It is a pair of true wireless earbuds. If you were searching hoping to find a Haylou smartwatch, models like the RS4 Plus or Solar Ultra are the ones you want instead.

Do I need a special app to use LDAC?

No app is required, but your phone or audio source needs to support the LDAC codec natively, and you may need to manually select it in your device’s developer or Bluetooth audio settings.

How does the S40 compare to the FlowBuds N55?

Both sit in a similar ANC tier, but the S40 pushes harder on spatial audio and adaptive EQ, while the FlowBuds N55 focuses more on straightforward call quality and battery efficiency.

Conclusion

The Haylou S40 earns its reputation as one of the stronger budget ANC earbuds in Haylou’s current lineup, particularly for anyone who values LDAC support and genuinely long battery life. Just make sure you know going in that this is an earbud, not a watch, before you order.

I’ve been covering budget electronics long enough to know which claims hold up and which ones do not survive a week of daily use.