What is the difference between Dolby Atmos and lossless sound quality? It is actually the one that most people should upgrade first.

On streaming platforms, "Dolby Atmos" and "Lossless" often appear side by side next to the same album, seeming like two versions of the same upgrade. In fact, these are two sets of unrelated technologies. One is about how the sound is "placed", and the other is about whether the sound is "compressed". Engadget author Adnan Ahmed broke down the two issues in an article published on August 28, and also gave his own preference.

Dolby Atmos is an object-based audio system that can position sound vertically and horizontally to create a stereo sound field. Traditional stereo can only place the sound between the left and right channels, but Dolby Atmos can accurately place an instrument or vocal at any point in the three-dimensional space. Lossless sound quality deals with another level: common formats such as MP3 and AAC sacrifice part of the audio data in exchange for smaller file sizes, which is destructive compression; lossless sound quality pursues bit-perfect playback, which theoretically allows the listener to hear the same content as the master tape.

Although the two operate independently, there are currently almost no streaming platforms that allow you to enjoy both at the same time. Most Dolby Atmos content is encoded using Dolby Digital Plus, which is destructive compression in itself; lossless sound quality relies on encoding formats such as FLAC and ALAC that completely retain the original data. Technically, there is Dolby TrueHD that can achieve both lossless and Atmos, but this type of encoding mainly appears on physical media such as Blu-ray discs, and is not currently used by streaming services.

For lossless sound quality to really take effect, there are more conditions than you might imagine.

Whether lossless sound quality is perceptible depends on whether the entire playback chain is in place: the streaming service must provide true bit-perfect playback, and the playback device must be able to handle the extra details. Although both Apple Music and Tidal can transmit lossless audio via Bluetooth, the signal will still be transferred by destructive encodings such as SBC and AAC before reaching the headphones. Therefore, to hear the true lossless effect, you must rely on a wired connection, which is also officially recommended by Apple. The exception is Qualcomm's aptX Lossless code, which can achieve bit-perfect transmission through Bluetooth, but only if an Android phone is used with a wireless headset that supports this technology.

When adjusting the sound quality in Apple Music or Tidal, you will often see numbers such as 16-bit/44.1kHz or 24-bit/192kHz. 44.1kHz and 192kHz are sampling rates, which represent the number of audio signal measurements per second; 16-bit and 24-bit are bit depths, which determine how detailed each measurement can be recorded. CD-quality lossless audio is 16-bit/44.1kHz, while Hi-Res Lossless exceeds CD specifications, such as 24-bit/96kHz or 24-bit/192kHz. To convert this digital information into sound that can be played by headphones, a digital-to-analog converter (DAC) is required. The built-in DAC in a mobile phone or laptop can usually handle CD-quality lossless content, but if you want to listen to Hi-Res Lossless, you may need an external DAC.

Author's opinion: In daily listening, Atmos is more effective than lossless

Adnan Ahmed bluntly stated in the article that this may be a "bold view" - in terms of daily listening, the improvement brought by Dolby Atmos is more obvious than lossless sound quality. At present, Apple Music, Tidal and Amazon Music Unlimited all have a certain size of Atmos music library, but to hear the effect, the device itself must support Dolby Atmos: all current Apple products support it out of the box, and Android phones need to check the specification sheet to confirm.

You don't need special headphones to listen to Atmos music, but a pair of headphones with good instrument separation and a wide sound field can make the effect more convincing. Ahmed mentioned that his AirPods Pro 2 are "unexpectedly good" in presenting spatial information. The processing methods of the two platforms are also different: Apple Music will tag the Atmos-supported tracks and automatically play the Atmos version when a compatible device is detected, which is the smoothest experience; Tidal lists the Atmos version and the stereo version separately, which is a little cluttered in browsing, but it also allows users to clearly choose which version they want to listen to.

Not every Atmos mix will bring an improvement, but once you encounter a well-mixed track, the difference will be quite direct. Ahmed mentioned that he particularly likes the Atmos remixes of The Weeknd, Daft Punk and Billie Eilish, and that the Dolby Atmos version of Lady Gaga's "Poker Face" "is like a completely different song", even with an extended outro and extra vocals.