If you spend thousands on a Dolby Atmos soundbar and thousands more on an OLED TV, but you're still using a cable designed for the original Sony Walkman era to connect them, then your surround sound is probably being very severely limited. The TOSLINK (optical) cable is the legacy port of the audio world.

It was revolutionary in the 80s, but in 2026, it's the equivalent of trying to stream 4K video over a dial-up modem. If you're using an optical cable, you can't use Dolby Atmos, DTS:X, or any form of lossless high-resolution audio, so it might be time for you to move to HDMI eARC.

Make the switch for your soundbars

You're missing out on precious quality

When it comes to technical specifications, optical cables have a maximum bandwidth of roughly 384Kbps to 1.5 Mbps. This is only enough for legacy surround sound, like standard Dolby Digital and DTS 5.1. In reality, when you are playing a modern movie, your TV has to crush that massive audio file into a compressed 5.1 signal just to fit it through the optical pipe. You are losing about 80% of the detail before it even reaches your ears. Optical cables have reached their bandwidth wall, and 5.1 just isn't good enough anymore for modern-day movies and surround sound systems.

Many users see Atmos on their Netflix screen and assume they're hearing it, but the hard truth is that Dolby Atmos and DTS:X require metadata that simply can't travel over an optical connection. Optical doesn't support Dolby Digital+, the carrier for streaming Atmos, or Dolby TrueHD, the carrier for Blu-ray Atmos.

If you're using an optical, your Atmos soundbar is just faking it with basic upscaling. You're not really getting spatial audio despite spending thousands on the gear. You're bottlenecking your entire sound setup thanks to a cable, which is probably the oldest piece of kit you've got in your home.

You might also find that you're encountering lip sync struggle and CEC loss. Realistically, optical is a one-way street, which means you don't get CEC. You can't use your TV remote to control your soundbar volume, so you're back to juggling two remotes like it's 2005.

There's also no auto sync that HDMI eARC provides. The latter has lip sync correction built in. Optical doesn't, which can lead to that annoying delay where the sound doesn't match the actor's lips perfectly when using HDMI 2.1 alongside the latest CEC indication protocol.

So what's the fix? Upgrading to HDMI eARC. Look for the HDMI (eARC) port on the back of your TV. The difference is that eARC, which stands for Enhanced Audio Return Channel, has a bandwidth of about 37MB/s, which is over 25 times the capacity of the top-end optical cables. This allows for uncompressed 7.1 sound, 24-bit or 192 kHz high-res audio, and true lossless Dolby Atmos.

If you're yet to make the upgrade to HDMI eARC, try it out, and you'll notice a whole world of difference when it comes to your sound quality. Optical just isn't the way forward anymore.

Don't toss out your cable anytime soon

Optical still serves a purpose

Legacy doesn't always mean obsolete. While HDMI eARC is the undisputed king of bandwidth, the TOSLINK optical cable remains the industry's favorite insurance policy. There are a few places where optical still wins, and a reason why it should have a permanent home in any enthusiast's cable drawer.

It's rare for 40-year-old technology to remain relevant, but optical audio survives because it does one thing that copper cables can't: it uses light instead of electricity. In a world of increasingly noisy high-powered electronics, that distinction is a lifesaver. Optical cables can be the savior of ground loops.

If you've ever heard a low, annoying hum or buzz sound coming from your speakers, especially when your PC's GPU is on load, you've likely encountered a ground loop. Copper cables, such as HDMI or RCA, create a physical electrical connection between your devices. If your PC and your amp are plugged into different outlets, they can have slightly different electrical potentials, creating a current loop that manifests as audible noise. Because TOSLINK is fiber-optic, there is no electrical contact between your source and your speakers. It provides isolation instantly, severing the loop and killing the hum. It can be the fastest way to clean your audio signal in a messy workstation these days.

Another situation is the vintage bridge. The high-end audio world of the late 90s and early 2000s produced some legendary analogue receivers and DACs that still sound better than many modern mid-range soundbars. If you own a classic piece of gear that lacks HDMI eARC, optical is your only high-quality digital bridge.

Lastly is the PC angle. Look at almost any high-end X870E or Z890 motherboard released in 2026, and you'll likely still see that glowing red optical port. While USB-C audio and DisplayPort are the standard for 120Hz gaming, they often come with driver issues or handshake problems that can cause audio to drop out when you alt-tab. Optical is driverless —it just works. Many PC gamers still use optical to connect to a desktop because it bypasses electrical interference from 500W GPUs and keeps the PC's internal noise away from their high-end headphones.

Don't spend hundreds on soundbars just to use an ancient cable

Time to move on from optical

The optical cable is the VGA port of audio. Yes, it's reliable, it's familiar, and it has its place with certain technology, but for the most part, it's holding you back, particularly when it comes to your surround sound system. Your ears deserve the bandwidth you already paid for. Switch to HDMI eARC and finally hear what your speakers are actually capable of. Don't toss the optical cable, though; keep it in a drawer ready for another day.