The WF-LS900N, also known as the Sony LinkBuds S, is the latest addition to Sony’s line of truly wireless earbuds. These earbuds are notable for their compact and lightweight design, which makes them 40% smaller than the flagship WF-1000XM4. The LinkBuds S offer advanced noise-cancelling capabilities in a convenient and discreet package, making them a solid choice for on-the-go listening.
Despite its smaller size and lower price point of $200, the Sony LinkBuds S offer a range of features similar to the more expensive WF-1000XM4, including active noise cancellation, ambient mode, LDAC and High-Resolution Audio Wireless, multipoint connection, 360 Reality Audio, and DSEE Extreme AI upscaling. These earbuds also claim to offer the best call quality of any truly wireless headphones from Sony, potentially making them an even better choice for making calls than the flagship model.
We happened to get a unit in the office, and after performing all due tests, this is what we felt about the Sony Linkbuds S –
Design
In comparison to Sony’s other fully wireless devices, the LinkBuds S are a refreshing change in terms of design. Most of them tend to have a bulkier, less comfortable fit, but the LinkBuds S are compact and lightweight, which makes them a much-needed improvement over the WF-1000XM4. They fit easily in your ears and can be worn all day without causing discomfort.
The charging case for the LinkBuds S is also smaller and thinner than the 1000XM4 case, making it more convenient to carry in your pocket. However, the case is not water resistant like the earbuds, which have an IPX4 rating.
There are three colour options available for the LinkBuds S: black, white, and beige, with an additional Earth Blue option available in select locations. The first three colours are fairly monotone and uninteresting, but the Earth Blue option, which is made from repurposed water bottles, has a unique hazy design.
Audio Quality
The LinkBuds S feature small 5mm dynamic drivers, which is a 17% reduction from the already small 6mm drivers on the WF-1000XM4. They offer Bluetooth 5.2 connectivity with support for SBC, AAC, and LDAC up to 32-bit, 96kHz, and 990Kbps.
In terms of sound, the LinkBuds S have a laidback, warm sound with a prominent but not overpowering bass response. The bass boost has a gentle curve that adds to the warmth and rumble of the recording without being too distracting. The mid-range performance is generally good, with vocals and instruments having a natural timbre and tonality. However, the upper mid-range and treble are a bit muted, which can obscure some instrumental detail and breathiness of vocals, resulting in a slightly duller sound that may not be suitable for all recordings.
Overall, the LinkBuds S offer a relaxing and pleasant listening experience, but their sound may not be as balanced as some other options, such as the Samsung Galaxy Buds 2 Pro or the AirPods Pro 2. You can improve the sound by using the EQ or the Bright preset, but if you want a more balanced sound out of the box, you may want to consider alternative options.
Noise Cancellation
The LinkBuds S offer excellent active noise cancellation (ANC) performance, using the same custom processor as the WF-1000XM4, although I was unable to confirm if this is actually the case as I did not have a pair of 1000XM4 to compare while testing the LinkBuds S. In comparison, the Google Pixel Buds Pro seemed to be only half as effective at cancelling noise, with ANC that seemed mostly perfunctory.
Sony’s ambient sound mode also works well enough, although it doesn’t sound completely accurate, especially at higher levels. I found it best to leave it at level 16 for a natural sound, with higher levels better for hearing every rustle of your clothes.
Latency and Microphone Quality
The LinkBuds S offer excellent recording quality for a pair of Bluetooth earbuds, with voices in quiet environments sounding very good and only a hint of a lisp from the noise reduction in the background. The quality is good enough to be mistaken for an entry-level wired headset microphone, which is a testament to their performance. Even in noisier environments, the LinkBuds S still perform well, with the algorithm effectively filtering out background noise once you start speaking. While your voice may suffer a bit and not sound as good as it does in a quiet room, it is still perfectly audible.
The only issue we had with the LinkBuds S was that while they do pass through some outside noise while you are speaking, it is not enough to make you hear your own voice clearly, which can make it awkward to speak. I found it much easier to speak with the ambient sound mode enabled, as it amplifies your voice before sending it through.
In terms of latency performance, the LinkBuds S offer decent performance, with minimal lag when watching videos on a phone or using latency-sensitive apps with AAC or LDAC at 330kbps and 660kbps. When paired with a PC using SBC, the LinkBuds S offer mostly fine latency performance, although there is a slight delay that is noticeable. Overall, the LinkBuds S offer decent latency performance that should be sufficient for most users.
Software and AI Features
The LinkBuds S can be controlled through Sony’s Headphones Connect app. This app has a ton of features, some of which are useful and others not so much. It can be slow to load and a bit confusing to navigate. However, one of the more useful features is the ability to activate multi-device pairing, which allows you to see all connected devices and previously linked devices in the app. Even if one of the devices is a PC, you can still control it through the app as long as it’s open on the second device.
The app also lets you adjust the ANC settings. Unlike before, you can’t control the strength of the ANC – it adjusts automatically. However, you can change the ambient sound level and enable voice-only attention mode. When you start talking, the Speak to Chat function automatically lowers the volume and activates ambient sound mode.
There’s also a six-band EQ with a variety of settings, and the DSEE settings are stored on the earbuds themselves, so any changes you make will carry over to any other device you pair them with. DSEE Extreme is an AI-based upsampling function that’s meant to restore data from compressed audio. It works directly on the earbuds, so it’s just upsampling the data coming from the phone, not the actual audio itself. It only works with codecs that are 48kHz or lower, like SBC, AAC, and LDAC set to 44.1kHz or 48kHz. It doesn’t work if you use LDAC at 88.2kHz or 96kHz.
This means that even if you’re playing 64kbps MP3 files, DSEE Extreme won’t be activated if you’re using LDAC in its default 96kHz mode. That’s because Sony says DSEE Extreme is for “upscaling compressed digital audio files in real-time”, but it’s actually just upscaling the Bluetooth data coming from the phone, not the source files.
The app includes a feature that allows you to set up HRTF for Sony’s 360 Reality Audio. This process involves taking pictures of your head and ears to create a personalized HRTF, or head-related transfer function, which helps to accurately map 3D audio sources for your unique head and ear shape. While this may be a cool feature, the truth is that 360 Reality Audio is a less popular format that is only supported by a limited number of streaming services for a limited number of tracks. Given Sony’s tendency to embrace proprietary standards, it might be time to switch to a more widely supported format like Dolby Atmos.
The touch sensors on these earbuds are super customizable. You can assign different functions to each one, like ANC, playback controls, and volume control. By default, the left earbud controls ANC and the right earbud controls playback, but the volume control isn’t assigned by default. You have to choose between a set of options for each earbud, rather than being able to assign specific gestures to individual features like on other earbuds. It’s a bummer, to be honest.
Battery Life
The LinkBuds S offer a claimed battery life of 6 hours of continuous playback with ANC enabled and a quick charge of 1 hour after just 5 minutes of charging. It’s worth noting that using the DSEE Extreme feature with AAC can reduce the battery life to 4 hours and 47 minutes, a significant decrease for a feature that does not significantly improve audio quality. Charging for these earbuds can only be done via cable, as the case does not have wireless charging capabilities.
Conclusion
The Sony LinkBuds S or the WF-LS900N are impressive truly wireless earbuds that excel in comfort, noise cancellation, and microphone quality. While the sound quality and battery life are decent, they are not the best in their class. The only issue is the app, which is becoming cluttered and messy and needs to be streamlined.
