HDMI ARC vs Optical: Formats, Control and Device Compatibility

HDMI ARC and optical can both carry television audio to a soundbar, amplifier, DAC or streamer. The decisive difference is rarely “which cable sounds better.” It is whether the connection must also carry volume commands, coordinate power and input switching, and deliver a format the receiving product can actually decode.

Evidence status: Primary-source Verified for the connector and format entries below. SoundPath Lab has not run a simultaneous TV-interoperability test across every listed product. When a manufacturer does not publish a clear codec table, the field is marked Unknown rather than inferred from the ARC or eARC label.

Direct answer

Choose HDMI ARC or eARC when one-cable TV control, CEC volume commands and automatic TV input behavior matter. Choose optical when the system needs a simple stereo PCM path, electrical isolation or a dependable fallback from HDMI handshake problems.

Do not choose by the socket name alone. An eARC input can still feed a two-channel product with a limited decoder, while an ARC product may accept Dolby Digital. The TV, source, cable and receiving device must agree on one format.

ARC, eARC and optical at a glance

The transport capability is only the outer boundary. A product advertised with HDMI eARC is not automatically an Atmos decoder, an AVR or a multichannel amplifier.

Verified product compatibility matrix

This matrix records only what current manufacturer material clearly supports. “Safe first setting” is a setup baseline, not a claim that every television uses the same menu wording.

Why the WiiM Amp row matters

The original WiiM Amp and the Amp Pro look similar and both use HDMI ARC, but their accepted TV formats are not the same. WiiM's current support material uses stereo PCM as the safe baseline for the original Amp while identifying PCM and Dolby Digital for Amp Pro and WiiM Ultra. The current WiiM 5.1 guide lists Amp Pro, Amp Ultra and Ultra as eligible hubs—not the original Amp.

That is a model-level compatibility difference, not a cable difference. If a TV is fixed to Dolby Digital, an original WiiM Amp may remain silent even though the HDMI handshake and volume control appear normal.

Read the full WiiM Amp vs Amp Pro vs Amp Ultra comparison before replacing a working amplifier.

Why eARC does not settle the Fosi or Eversolo decision

Fosi markets the S3's HDMI eARC input as part of a simple 2.1 system, and Eversolo documents ARC/eARC input on Play. Those statements establish the connection and intended role. They do not, by themselves, publish the complete accepted-codec set.

SoundPath Lab therefore does not fill those cells with Dolby, DTS or lossless-format claims. A buyer who needs more than stereo PCM should obtain an exact, current answer for the model and firmware before the return window closes.

For the Fosi decision, also read Fosi S3 vs WiiM Pro Plus. It separates the S3's useful HDMI and XLR hardware from its wider software-maturity questions.

Choose by the system you already own

Keep optical when it already solves the problem

If the TV outputs stable stereo PCM to an existing DAC, amplifier or powered speaker and a second remote is acceptable, replacing the path only to obtain an ARC label may add complexity without improving the result.

Optical also breaks the electrical connection between the TV and audio system. That can be useful when HDMI or analogue wiring contributes to a hum loop.

Choose ARC/eARC when everyday control is the missing function

ARC is most valuable when the household expects the TV remote to control volume, the audio system to wake with the television and the TV input to become the normal default. These behaviors depend on HDMI-CEC and product implementation; they are not guaranteed by bandwidth alone.

If the system combines TV, music and a subwoofer, compare the three clean TV-and-music system architectures before deciding whether the new device should be a preamplifier hub or a speaker-driving amplifier.

Do not feed passive speakers from a streamer or DAC

WiiM Ultra, Fosi S3, Fosi ZD3 and Eversolo DMP-A6 Gen 2 provide line-level outputs. They still require powered speakers, an integrated amplifier or a power amplifier. WiiM Amp, Amp Pro, Amp Ultra and Eversolo Play contain speaker amplification.

This role difference is more important than a small difference in digital-input specification. The wrong role can leave a system with no way to power its speakers or with two volume controls in series.

A safe setup sequence

1. Connect the TV's port labelled ARC or eARC to the audio product's specifically labelled ARC/eARC port. An ordinary HDMI input is not interchangeable.
2. Enable HDMI-CEC and ARC/eARC on both devices. CEC may use a brand name such as Anynet+, Simplink or Bravia Sync.
3. Select the external audio system in the TV menu and the TV/ARC input on the receiving product.
4. Set the TV to stereo PCM for the first test. Use a built-in TV app before adding a game console, streaming box or disc player.
5. Confirm stable sound and TV-remote volume control. Then test automatic wake, input return and lip-sync.
6. Only after PCM works, enable Dolby Digital or another format that the exact receiver explicitly documents.
7. If sound disappears, return to PCM. That isolates a format mismatch from a cable, port or CEC failure.
8. If HDMI remains unreliable, test optical PCM. A working optical path can keep the system usable while the HDMI behavior is investigated.

For symptom-by-symptom recovery, use the separate HDMI ARC/eARC troubleshooting guide.

What remains unknown

SoundPath Lab has not verified every television pairing, restart-volume state, CEC brand combination, firmware version or automatic input-priority rule for the products in this matrix. The exact accepted ARC/eARC codec set remains unclear in the public material reviewed for Fosi S3, Eversolo DMP-A6 Gen 2 and Eversolo Play.

Those are documentation gaps, not proof that a format fails. Owners can help close them by submitting the television model, source device, TV output setting, receiver firmware, connection type and a repeatable result. One anonymous report should not become a universal compatibility claim.

Bottom line

Choose the connection that completes the whole control and format path.

• Use ARC/eARC when TV-remote volume, coordinated power and automatic TV behavior matter.
• Use optical when a stable stereo PCM link, isolation or a fallback is more valuable.
• Treat the receiving product's codec table as authoritative over the connector label.
• Treat missing codec documentation as Unknown, not as implied support.
• Keep existing equipment when it already provides a stable path and the new connection does not solve a real problem.

Primary sources

• HDMI Licensing Administrator — HDMI and eARC information
• WiiM — How to use the audio inputs of WiiM Ultra
• WiiM — Setting up a Dolby 5.1 home theater
• WiiM — Amp Pro product page
• WiiM — Ultra overview and specifications
• Fosi Audio — S3 product page
• Fosi Audio — ZD3 product information
• Eversolo — DMP-A6 Gen 2 product page
• Eversolo — Play product page

Last evidence review: 14 September 2026.