Why connection choice matters for sound quality and formats
Choosing between eARC and optical determines which audio formats a soundbar can receive intact. eARC is the modern HDMI return channel designed to carry high-bitrate multichannel and object-based audio without re-encoding. Optical (Toslink), an older digital interface, is constrained by the limitations of S/PDIF and typically carries compressed 5.1 streams or stereo PCM only. Understanding those differences up front will prevent disappointments when expecting Dolby Atmos or DTS:X from streaming apps or disc players.
Step 1 — confirm ports, firmware and device roles
Locate the TV’s HDMI port labeled eARC or ARC and the soundbar’s corresponding HDMI port. If a TV has eARC and the soundbar only ARC (or vice versa), the connection will fall back to ARC capabilities. Before wiring, update both devices to the latest firmware — many audio pass-through and compatibility fixes arrive via updates. Decide which device will be the hub: for full format support, connecting the source directly to the soundbar/AVR and then sending video to the TV is often the safest choice because it lets the soundbar receive the native bitstream from the source.
Step 2 — cable choices and physical connections
For eARC, use a certified Ultra High Speed HDMI cable or a high-quality HDMI 2.1 cable; these are designed to handle the higher bandwidth eARC can carry. Run a single HDMI from the soundbar’s HDMI eARC out to the TV’s HDMI eARC in. For optical, connect a Toslink cable from the TV’s optical out to the soundbar’s optical in. Keep optical cable runs short where possible; optical signals degrade on very long runs and cheap connectors can introduce dropouts.
Step 3 — TV and soundbar settings for pass-through and output
On the TV, set audio output to HDMI eARC or bitstream/passthrough if those options are present. Disable the TV’s internal speakers to avoid echo unless you intend to use them in a calibrated surround mode. On the soundbar, choose the appropriate input and enable eARC support. If offered, select bitstream to allow the soundbar to decode formats like Dolby TrueHD or DTS-HD MA rather than forcing downmix to PCM.
Bandwidth limits and format compatibility: what to expect
eARC carries much higher bandwidth than optical and supports uncompressed multichannel PCM, lossless surround formats and object-based audio such as Dolby Atmos and DTS:X, provided both TV and soundbar advertise support. Optical is limited by S/PDIF bandwidth and rarely passes beyond compressed 5.1 (Dolby Digital, DTS) or stereo PCM. Many streaming apps use Dolby Digital Plus for Atmos-like tracks on TVs; those can sometimes pass over optical as a compatible compressed stream, but true bit-perfect Atmos from Blu-ray discs requires eARC or a direct HDMI connection from the source to the soundbar.
Fixing lip-sync, CEC issues and device negotiation
Enable HDMI-CEC (different brands use different trade names) to allow the TV remote and devices to control one another, but be prepared to toggle it off if devices misbehave. If audio lags video, use the TV’s audio delay or the soundbar’s lip-sync adjustment; many TVs also offer a frame-delay or game mode to realign A/V. If the TV reports limited audio formats, try changing the TV’s audio output to passthrough or connecting the source directly to the soundbar to bypass the TV’s audio processing. Firmware updates frequently resolve negotiation bugs between TV, soundbar and source devices.
Compatibility tips for Dolby Atmos and DTS:X
Confirm both the TV and soundbar explicitly state support for the target format. Dolby Atmos can be delivered as a lossless track (Dolby TrueHD+Atmos) from physical media or as a compressed bitstream (Dolby Digital Plus+Atmos) from many streaming services; eARC is required for lossless Atmos. DTS:X support varies widely; some TVs strip or refuse to pass DTS signals to the eARC output, so routing the source directly to the soundbar is often necessary for DTS:X. If the soundbar supports virtual Atmos processing, it may render object-based metadata even when fed downmixed audio, but this is not a replacement for native multichannel decoding.
Troubleshooting checklist and best practices
If audio is missing or limited to stereo: check that the HDMI cable is connected to the eARC ports, ensure audio output is set to passthrough/bitstream and verify firmware is current. If dropouts occur, replace the HDMI cable with a certified Ultra High Speed cable and keep optical runs short. When in doubt, connect the source directly to the soundbar and use the soundbar’s HDMI output to feed the TV — that preserves the source’s native audio format and avoids TV processing that can block high-bitrate streams.
Applying these steps will maximize the odds of getting full multichannel and object-based audio from the chosen sources while keeping lip-sync and remote control behavior predictable.
