What is audio passthrough? It is a setting on a streaming stick, disc player, game console, or TV that tells the device to skip decoding the soundtrack itself and forward the original encoded audio stream, unchanged, to a connected soundbar or AV receiver instead. Turn it on and that receiver handles the decoding, so formats like Dolby Digital Plus, Dolby TrueHD, or DTS arrive intact. Turn it off, and the source decodes first, which on many devices means flattening surround into two channels before the signal ever reaches your speakers.
That single choice, decode here or decode there, is the whole idea. Everything else in this guide is about knowing which side of that choice you actually want, and how to tell when a device has quietly made the wrong one for you.
Why This Setting Exists at All
A movie or show’s soundtrack does not leave the source device as plain stereo or 5.1 audio. It leaves as an encoded stream, something like Dolby Digital, Dolby Digital Plus, Dolby TrueHD, or DTS, packed with more channel information than a basic connection can carry unprocessed. Something in the chain has to turn that encoded stream into sound, and that decoding job can happen in one of two places: on the source device, or on the receiver at the end of the cable.
Manufacturers default many devices to decode on the source, because it guarantees compatibility. A device that decodes everything itself and outputs plain stereo, or basic PCM audio, will work with a bargain television’s built-in speakers just as easily as a full home theater rig. The cost of that safety is that any format the source decodes internally usually gets simplified in the process, and surround detail gets left behind.
Passthrough flips that default. Instead of decoding, the source hands off the untouched, compressed stream, technically called a bitstream, and lets a downstream device that is built for the job do the decoding. The technical distinction between that bitstream approach and the decoded PCM approach, along with the cases where PCM is actually the better choice, is covered in bitstream vs PCM.
What Changes When Passthrough Is On vs Off
| Passthrough on | Passthrough off | |
|---|---|---|
| Who decodes | The soundbar or AV receiver | The source device (stick, player, console, or TV) |
| What travels over the cable | The original encoded stream (bitstream) | Decoded audio, often stereo or basic PCM |
| Surround detail | Preserved, including Dolby Atmos or DTS:X where supported | Usually reduced, since the source picks a safe, compatible output |
| Best connection | HDMI, ideally with ARC or eARC | Any connection, including older optical links |
| Risk | Silence if the decoder downstream cannot handle the format | None from a compatibility standpoint, but you lose full surround |
When You Want Audio Passthrough On
Passthrough earns its keep when you already own equipment built to decode surround formats and you want the source device to stop getting in the way. That means a soundbar or AV receiver that lists Dolby Digital Plus, Dolby TrueHD, DTS-HD Master Audio, or DTS:X in its own specifications, connected over HDMI, and ideally over HDMI ARC or eARC rather than an older optical cable. If that describes your setup, passthrough is what lets a Blu-ray disc’s lossless track, or a streaming app’s Dolby Atmos mix, reach your receiver as it was mastered instead of arriving pre-flattened.
Which exact format shows up depends on the source. Streaming platforms typically deliver Dolby Atmos inside Dolby Digital Plus, while Blu-ray discs typically carry it inside Dolby TrueHD, and the two have different bandwidth needs and different connection requirements. The practical difference between them, and which one your own gear can actually decode, is broken down in Dolby Digital Plus vs TrueHD.
When You Don’t Want It
Passthrough is the wrong setting in three common situations. First, if the audio is going straight to a TV’s built-in speakers with no soundbar or receiver in the chain, there is nothing downstream to decode the stream, so decoding at the source is the only way to hear anything at all. Second, if the receiver or soundbar’s spec sheet does not list the format your content uses, passing that format through produces no fallback and often no sound, since passthrough has no safety net the way decoding does. Third, on an older optical (S/PDIF) connection, bandwidth is limited enough that the higher-bitrate lossless formats, including Dolby TrueHD, cannot travel over it regardless of the setting, so forcing passthrough there just risks dropped audio instead of gaining anything.
How to Turn Audio Passthrough On
The general process is the same across most streaming sticks, consoles, and disc players, even though the exact menu wording differs by device and changes between software versions:
- Confirm what your receiver or soundbar decodes. Check its manual or product page for the format names, Dolby Digital Plus, Dolby TrueHD, DTS-HD Master Audio, DTS:X, spelled out. A logo alone is not a guarantee.
- Confirm the connection type. HDMI is required for the higher-bitrate formats; eARC is built specifically to carry them, while plain optical or older ARC connections cannot.
- Open the source device’s audio settings. Look for an audio output, Dolby output, or HDMI audio format setting, and choose bitstream, passthrough, or an automatic mode that follows the content.
- Confirm it worked by reading the receiver’s badge, not by ear. The soundbar or receiver’s display, not the streaming app, tells you which format actually arrived and got decoded.
Menu names and locations vary enough by platform that a general checklist only gets you so far. On Amazon Fire TV devices specifically, the setting sits under the audio section as a Dolby output option, and the exact steps, along with the reasons a stick can silently downmix to stereo even with the right cable, are walked through in Fire Stick audio passthrough settings.
What Dolby and Amazon Say About How This Actually Behaves
Two points from manufacturer documentation, explain behavior that trips people up.
Dolby’s own professional documentation describes Dolby TrueHD as a fully lossless format used on Blu-ray and UHD Blu-ray discs, and describes Dolby Digital Plus as the compressed format that streaming and broadcast services use to deliver surround sound, including Dolby Atmos, at a data rate a typical internet connection can sustain. That difference in size is exactly why a disc player can pass a lossless track straight to a receiver over HDMI, while a streaming app relies on a smaller, compressed stream instead: the physical connection and the delivery method both have to match the format’s bandwidth needs.
Amazon’s own Fire TV developer documentation states that Fire TV Edition speakers support stereo output by default, and that apps stream surround sound only when the platform reports that a sound bar or AV receiver is connected over optical or HDMI and passthrough is enabled. In other words, when passthrough is off, the app never requests a surround stream in the first place. That is why toggling a “surround” setting on the soundbar itself does nothing if the source was never sending surround audio to begin with; the setting that matters lives upstream, on the source device.
Passthrough Is Not the Same as “Louder” or “Better” by Itself
It is worth separating two things that get confused. Passthrough decides where decoding happens, not how good the source material is. A poorly mixed soundtrack passed through untouched is still a poorly mixed soundtrack, just decoded by a different box. What passthrough guarantees is that whatever surround detail exists in the original stream, extra channels, height information for Dolby Atmos or DTS:X, has a chance to survive the trip to your receiver instead of being discarded early by a source device optimized for the widest possible compatibility.
FAQ
What is audio passthrough on a TV?
It is a setting that lets a TV forward an encoded audio stream, such as Dolby Digital, unchanged to a soundbar or receiver connected over HDMI ARC or eARC, instead of decoding the sound itself and sending a simplified version out.
Does turning on audio passthrough affect picture quality?
No. Passthrough is an audio-only setting. It changes how the sound is decoded and does not touch video processing, resolution, or frame rate.
Why did my sound disappear after I turned on passthrough?
Passthrough sends the encoded stream to whatever is downstream with no fallback. If your soundbar or receiver cannot decode that specific format, or if the connection (optical, for example) cannot carry it, the result is often silence rather than a simplified stereo signal.
Is audio passthrough the same thing as bitstream?
They describe the same underlying mechanism from two angles. Passthrough is the behavior, letting an encoded stream travel through unmodified, while bitstream is the technical name for that encoded stream itself. Menus sometimes label the same option “bitstream” instead of “passthrough.”
Should I leave audio passthrough on all the time?
Only if your soundbar or receiver reliably decodes the formats your content uses and the connection supports them. If you regularly lose sound after enabling it, an automatic mode, where the source device decides per title, is usually the safer default than forcing passthrough everywhere.
