You're sitting at your laptop, same song, same streaming service, same earbuds you were just using on your phone. Something is off. The bass is softer, slightly muddy. The highs have gone a bit dull. You tap the earbud, check the volume, wonder if you're losing your mind.
You're not. The earbuds are fine.
The invisible middleman nobody mentions
Wireless audio doesn't teleport from device to speaker. Bluetooth compresses the audio signal, ships it wirelessly, then decompresses it on the other end. That compression is handled by a codec, and which codec your earbuds actually use depends entirely on what both devices agree to negotiate when they pair.
Think of it like two people deciding which language to speak. Your earbuds might be fluent in four: SBC, AAC, aptX, and LDAC. Your phone might speak three of those. Your laptop might only speak one. So they default to the one they share, which is almost always SBC, Bluetooth's original lowest-common-denominator codec from the late 1990s.
SBC caps out around 328 kbps and introduces audible compression artifacts, especially in the midrange. AAC, which most iPhones push by default, runs more efficiently and sounds noticeably cleaner. Sony's LDAC, used on many Android flagships, can hit 990 kbps.
That's not a small gap.
It's the difference between a proper hardcover and a paperback edition of the same book, except the paperback is also missing a few pages. So when your Sony WF-1000XM5s pair with a Samsung Galaxy phone that supports LDAC, you're getting a rich, high-bitrate stream. When those exact same earbuds pair with a Windows laptop that only supports SBC, you're hearing a noticeably compressed version of the same file. The earbuds didn't change. The handshake did.
One scenario that makes this concrete
Take Maya and Dom. They buy the same pair of earbuds on the same day. Maya uses hers with a recent Android phone that supports aptX HD. Dom uses his exclusively with a MacBook Pro. Maya thinks the earbuds are exceptional. Dom thinks they're decent, and quietly wonders why the reviews raved so hard.
Dom isn't imagining things, and honestly, macOS deserves some blame here. His MacBook supports AAC over Bluetooth, which is actually pretty good. But macOS has a maddening habit: when a Bluetooth device is set as both audio output and microphone input at the same time, the system quietly downgrades the codec to SCO (Synchronous Connection-Oriented), a voice-call protocol that caps audio quality at telephone levels. Dom hopped on one video call with his earbuds in, and macOS left them in that degraded mode for the rest of the session.
Restarting the Bluetooth connection fixes it. Most people never figure that out.
What people consistently get wrong
The common assumption is that expensive earbuds always sound better, full stop. Wrong. A $300 pair running SBC on a codec-stingy laptop can genuinely sound worse than an $80 pair running aptX on a compatible phone. Hardware quality matters, yes, but the codec is the ceiling, and the ceiling is set by the weakest link in the chain.
People also assume Bluetooth 5.0 or 5.3 means better audio. It doesn't, not directly. Newer Bluetooth versions improve range, connection stability, and power efficiency. They say nothing about which audio codecs are supported. A device can have Bluetooth 5.3 and still only offer SBC. The version number and the codec are completely separate specs, and conflating them is how people end up blaming their earbuds for their laptop's limitations.
How to actually check what you're getting
On Android, enable Developer Options, then look for "Bluetooth Audio Codec" under wireless settings. It shows you the live codec your earbuds are using right now. Seeing LDAC or aptX HD? Good. Seeing SBC on a device that should support better? That's worth investigating.
On a Mac, hold Option and click the Bluetooth menu bar icon. It'll show the codec next to your connected device. AAC is the best macOS typically offers, and it's genuinely acceptable for music. If you see anything labeled SCO or "hands-free," that's the video-call downgrade. Disconnect, reconnect, and don't open a microphone app.
Windows is messier. Codec support depends on the Bluetooth chipset and drivers, not the OS version. Some laptops support aptX through a Qualcomm chip; many don't. Third-party tools like Bluetooth Tweaker can surface what's actually being negotiated.
If you've never checked your active codec, you may never have heard your earbuds at their best. Your earbuds have a peak version of themselves, and that version only appears when both devices in the chain speak the same high-quality language. The sound you know from your phone might be something your laptop is structurally incapable of delivering. That's not a flaw in the earbuds. It's a ceiling built into the connection itself, and most people never even know it's there.