Wired vs wireless headphones: where the sound is actually made

Two completely different things, depending on which wire. A 3.5 mm jack carries analogue audio: a voltage that is already a picture of the sound wave, which the driver in the earcup follows directly. On a passive headphone that is the end of it, because there is nothing inside drawing power to do anything else. A headphone with its own battery is a different case, and it can amplify, equalise or cancel on top of the analogue signal it is handed.

A USB-C cable carries digital data, which is to say numbers. So does a Bluetooth link. Numbers are not sound, and something at the far end has to convert them, which means that anything connected digitally must contain its own conversion and amplification hardware or it will produce silence.

This is why a 3.5 mm headphone works on absolutely anything with a matching hole and a USB-C one does not always work on the next device you try. One is a passive device that accepts a finished signal. The other is a small computer that has to be talked to.

In your source device for a 3.5 mm connection, and in the headphones for everything else. Turtle Beach, which manufactures both kinds, describes it plainly for each: with a 3.5 mm headset the audio is processed by your device's built-in converter and amplifier before reaching the headset's drivers, while a USB headset has its own built-in converter and audio processing hardware and handles the signal digitally inside the headset rather than relying on your device's sound card.

SoundGuys reaches the same conclusion from the other direction, describing USB audio's main change as moving the converter and amplifier from inside the source into the headphones or the dongle. Two sources, same mechanism, and it is the single most useful thing to understand about this topic.

The consequence is a real shift in who is responsible for the sound. On a 3.5 mm connection you are hearing your phone's audio circuitry as much as the headphones, which is why the same earbuds can sound different on a laptop and a phone. Move to USB-C or Bluetooth and the headphone maker owns that circuit, so what you get is consistent across devices and only as good as the maker chose to make it.

One trap if you use an adapter. SoundGuys distinguishes active USB-C adapters, which contain a converter and amplifier of their own, from passive ones, which simply pull an analogue signal straight out of a phone that happens to still produce one. The passive kind is cheaper and depends entirely on a phone feature that many devices no longer have, which is why a cheap adapter sometimes produces nothing at all.

Because the link does not have the bandwidth for uncompressed audio, so the sound is encoded before it is sent and decoded when it arrives. Which encoder gets used is negotiated between the two devices, and SoundGuys makes the point that both your phone and your headphones have to support the same one, or the connection falls back to whatever they share.

On the classic Bluetooth path that carries stereo to most headphones, that fallback is SBC, which the A2DP profile makes mandatory. What SBC actually runs at depends on the implementation rather than on the codec, which is why published figures for it disagree, so take the ladder above it as the useful part: AAC at around 250 kbps, aptX at 352 or 576 in its HD version, and Sony's LDAC which can reach 990 but, as SoundGuys notes, frequently defaults to 330 on a phone. LE Audio is a different path with a different mandatory codec, LC3, and the Bluetooth SIG says plainly that an LE Audio device is not required to support the classic one at all.

Does it matter? Less than the numbers suggest and more than nothing. None of it has been heard by anybody here, so whether you would pick out the difference between 320 and 990 kbps is not ours to say. What we can tell you is the practical shape of the problem: the codec is chosen by whichever pairing is weakest, and buying headphones with a good codec buys you nothing if your phone does not have it.

Here is the uncomfortable part. Good luck finding a codec list on a product page at all. The specification that decides how good a Bluetooth connection is allowed to sound is the one routinely left off, which tells you roughly how much the industry expects buyers to look for it.

The encoding and decoding, plus the buffer that sits between them to survive interference. Every one of those steps takes time, and the total is what you notice when a video's audio drifts out of step with the picture. It is not the radio being slow in any simple sense.

The figures are not flattering. SoundGuys puts aptX Low Latency under 40 milliseconds and most of the codecs it compares above that, which is a useful reference point: 40 ms is roughly two and a half frames of a 60 fps video. Video apps hide this by shifting the picture to match, which is why a film is fine and a game is not.

A 2.4 GHz dongle avoids most of it by using a link designed for one job, which is why the dongle-based products here are both gaming headsets. And an analogue cable adds none of that, because nothing is being encoded, though whatever delay is left still belongs to the source and to any processing the headphones do. If you play anything competitive, that ordering is what to shop on, and which products offer which connection is worked through in Choosing headphones by connection: Bluetooth, 3.5mm, USB or 2.4GHz.

Yes, and now you can see why rather than having to take somebody's word for it. Switching a dual-mode headphone from Bluetooth to its cable does two things at once: it removes the compression, and it hands the conversion job to a different piece of hardware. Either change alone would be enough to make a difference measurable.

That is not the same as saying the cable sounds better. On a good wireless headphone the internal converter and amplifier were chosen by the manufacturer to suit its own drivers, and on a cable you get whatever is inside the laptop you plugged into. Plenty of headphones are voiced around their wireless path and are the odd one out when wired.

What we will not do is rank them for you. There is no listening behind this page, and a claim about how a pair sounds on two connections needs ears and a quiet room. Three products here let you run the comparison instead of taking anyone's word for it: HyperX Cloud III accepts all three wired paths, and the two connector versions of Apple EarPods (USB-C) sit beside each other at the same price.

A cable is a good choice when you want to avoid a Bluetooth link, keep charging out of the routine, or use passive headphones with an existing audio output. For latency-sensitive work, check the source and any audio processing too; the cable is not the whole signal path.

There is a related point that catches people out, and it is about power rather than about the cable. Active cancellation needs a live supply, and an ordinary analogue headphone connection does not provide one, so a cancelling headphone either takes power from a USB cable or carries a battery of its own. The battery route is why several headphones sold as wireless keep an analogue socket and go on cancelling through it. Which products do which is worked through in Can wired headphones have noise cancelling? Yes, but something has to power them.

And there is one thing a radio alone cannot do at any price: work when the battery is flat. A headphone with a jack as well can, though what survives is plain passive audio with the cancellation and the EQ switched off, which is how Bose describes its own behaviour without power. You can compare models with wired and wireless options beside keyboards and mice in the setup builder.