HDMI Passthrough: What Your Soundbar Sends to the TV

HDMI passthrough on a soundbar means the soundbar receives a video signal from a source (like a streaming stick or game console), extracts the audio for its own speakers, and then sends the untouched video onward to your TV through a second HDMI cable. In short, your soundbar sends the original video signal to the TV while keeping the audio for itself.

Why Passthrough Exists

Before HDMI ARC (Audio Return Channel) became common, connecting a soundbar to a TV was simple: you ran an optical cable from the TV to the soundbar for audio, and the video went straight to the TV. But that setup had a problem—many TVs only output stereo or compressed 5.1 over optical, not the lossless formats like Dolby TrueHD or DTS-HD Master Audio that Blu-ray players and game consoles produce.

HDMI passthrough solves this by putting the soundbar between the source and the TV. The source plugs into the soundbar’s HDMI input, and the soundbar passes the video through to the TV while decoding the audio itself. This way, the soundbar can handle lossless audio formats that the TV might not support, and you don’t need to switch inputs on the TV—the soundbar acts as a hub.

How Passthrough Works

When you connect a device to a soundbar’s HDMI input, the soundbar does three things:

Receives the full HDMI signal (video + audio) from the source.
Extracts the audio track and plays it through its speakers (or sends it to wireless surround speakers).
Re-transmits the video signal unchanged to the TV via the HDMI output (labeled “TV OUT” or “eARC/ARC”).

The video is not altered—it remains in the same resolution, frame rate, and color format. The soundbar simply acts as a pass-through, like a repeater. However, the soundbar must be powered on for passthrough to work; if it’s off, most models will not send the signal to the TV.

Passthrough vs. ARC and eARC

Passthrough and ARC are often confused, but they solve different problems. ARC (and its newer version eARC) lets audio travel from the TV to the soundbar through the HDMI cable. Passthrough, on the other hand, lets video travel through the soundbar to the TV.

Here’s a typical setup with passthrough:

Source (e.g., Apple TV, PS5) → HDMI cable → Soundbar HDMI IN
Soundbar HDMI OUT (eARC) → HDMI cable → TV HDMI ARC/eARC port

With ARC, you’d connect the source directly to the TV, then use an HDMI cable from the TV’s ARC port to the soundbar’s ARC port. Audio from the TV’s built-in apps or from the source goes back to the soundbar. ARC has bandwidth limitations—it can carry compressed 5.1 (like Dolby Digital) but not lossless formats. eARC, introduced with HDMI 2.1, can carry lossless audio and higher bandwidth.

If you have a soundbar with multiple HDMI inputs, passthrough is the better choice for sources that need lossless audio. If you only use the TV’s built-in apps, ARC/eARC is sufficient.

What Video Formats Can Pass Through?

Most soundbars with passthrough support HDMI 2.0, which handles 4K at 60Hz with HDR10 and Dolby Vision. Newer models may support HDMI 2.1, allowing 8K at 60Hz or 4K at 120Hz, plus variable refresh rate (VRR) and auto low latency mode (ALLM) for gaming.

However, not all soundbars pass through every feature. Some budget models may strip HDR or reduce the refresh rate. Always check the soundbar’s specs for “HDMI 2.1” and “eARC” to ensure it supports the latest video features. If you have a gaming console that needs 4K/120Hz, you need a soundbar with HDMI 2.1 inputs and outputs.

Common Problems and Troubleshooting

Passthrough can sometimes be finicky. Here are common issues and fixes:

No picture on TV: Make sure the soundbar is powered on and set to the correct input. Check that the HDMI cable from the soundbar to the TV is plugged into the TV’s HDMI ARC port (if required).
Video flickers or drops: Try a different HDMI cable, preferably one certified for the bandwidth you need (e.g., “Ultra High Speed” for HDMI 2.1). Loose connections are also a culprit.
Audio sync issues: Some soundbars have a lip-sync adjustment. Also, try disabling any video processing on the TV (like motion smoothing) that can add delay.
HDR not passing through: Check if the soundbar’s HDMI input supports HDR. Some older models only pass through HDR10, not Dolby Vision. Also, enable “Enhanced HDMI” on the TV if available.
No sound from the source: Make sure the source is set to output bitstream audio (not PCM) if you want the soundbar to decode it. If the source is set to PCM, the soundbar may only get stereo.

How to Choose a Soundbar for Passthrough

When shopping for a soundbar, look for these features to ensure good passthrough:

Number of HDMI inputs: At least two if you have multiple sources.
HDMI version: HDMI 2.1 for 4K/120Hz or 8K, HDMI 2.0 for 4K/60Hz.
eARC support: Even if you use passthrough, eARC is useful for TV apps.
HDR format support: Check if it passes Dolby Vision, HDR10+, or both.
VRR/ALLM: For gaming, these features reduce input lag and screen tearing.

Also, consider whether the soundbar can decode the audio formats you need (Dolby Atmos, DTS:X, etc.). Passthrough only carries video; the audio decoding happens in the soundbar.

Passthrough vs. Direct Connection

An alternative to passthrough is connecting the source directly to the TV and using eARC to send audio to the soundbar. This works well if your TV and soundbar both support eARC, because eARC can carry lossless audio and even Dolby Atmos. The advantage is that you don’t need to worry about the soundbar passing through video features—the TV handles the video directly.

However, eARC has a few downsides: it may introduce slight audio delay, and not all TVs support eARC on all HDMI ports. Also, if you have multiple sources, you might run out of HDMI ports on the TV. Passthrough gives you more flexibility by acting as a switch.

In practice, if your TV and soundbar both have eARC, either setup works. But for gamers who need VRR and 4K/120Hz, passthrough with an HDMI 2.1 soundbar is often simpler, as it avoids any potential eARC handshake issues.

Frequently Asked Questions

Does HDMI passthrough degrade video quality?

No, HDMI passthrough does not degrade video quality if the soundbar supports the video format. The video signal is re-transmitted digitally without any processing, so it remains bit-for-bit identical. However, if the soundbar does not support a feature like VRR or Dolby Vision, it may strip that feature from the signal.

Can I use passthrough with a soundbar that only has one HDMI port?

If the soundbar has only one HDMI port, it’s likely an ARC/eARC port, not a passthrough port. In that case, you cannot connect a source to the soundbar; you must use ARC to get audio from the TV. For passthrough, you need at least one HDMI input and one HDMI output.

Why is there no picture when the soundbar is off?

Most soundbars do not pass through video when they are in standby mode. This is because the HDMI repeater circuit is powered off. You’ll need to leave the soundbar on to get a picture, or use a direct connection to the TV instead.

Does passthrough work with all HDMI cables?

Passthrough works with any HDMI cable that meets the bandwidth requirements of the video signal. For 4K at 60Hz, a High-Speed HDMI cable is sufficient. For 4K at 120Hz or 8K, you need an Ultra High-Speed cable. Using a low-quality cable can cause flickering or no signal.

What is the difference between HDMI passthrough and HDMI ARC?

HDMI passthrough sends video from a source through the soundbar to the TV. HDMI ARC (Audio Return Channel) sends audio from the TV back to the soundbar. They are complementary: passthrough handles video from external sources, while ARC handles audio from the TV’s built-in apps or from sources connected directly to the TV.

Can I use passthrough to connect a soundbar to a projector?

Yes, passthrough works with projectors as long as the projector has an HDMI input. The soundbar passes the video to the projector, and the projector displays it. Just ensure the soundbar supports the projector’s resolution and refresh rate.

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