The Neo Matrix Range has dedicated digital audio outputs — Stereo L/R, coaxial (S/PDIF) and optical (TOSLINK) — on the rear panel that pass audio extracted from the HDMI inputs. If these outputs have stopped working across multiple sources, this article covers the diagnostic steps and when to contact support.
This article covers the rear-panel coaxial and optical audio breakout ports, not audio carried over HDBaseT to receivers. If the issue is no audio at a zone display connected via HDBaseT, see
Neo Matrix No Signal Troubleshooting.
How the Audio Outputs Work
The Neo Matrix extracts audio from HDMI input sources and makes it available on the coaxial and optical outputs. These outputs are typically used to feed a separate audio distribution system such as a ProAudio matrix or a third-party amplifier. The optical port LED on the rear of the matrix should be lit (red) when the port is active.
Step-by-Step Diagnosis
1
Confirm the source is producing audioTest with multiple source devices — Apple TV, Blu-ray, console etc. If none of the sources produce audio on the matrix outputs, the fault is likely either in the matrix or the configuration. If one specific source has no audio but others do, the issue is likely with that source's audio format, EDID settings or configuration.
2
Check the optical port LEDLook at the rear of the matrix. The optical port should have a visible red light when active. If the LED is completely unlit across all sources, this suggests the optical output section has failed — this is likely a hardware fault. Note whether the LED is lit and report this to support.
3
Check source audio format settingsSome streaming devices default to Dolby Atmos or DTS:X output. If the downstream amplifier or audio system does not support these formats, it may output silence rather than decode. Many neo matrices are also not capable of Dolby Downmix, check your product manual to verify if yours can. Set source devices to output 2-channel PCM as a test — this is the most universally compatible format and will confirm whether the issue is format-related or hardware.
4
Check EDID settingsThe EDID presented to the source device tells it what audio formats the downstream system supports. If the EDID is incorrectly set, the source may output a format that nothing in the chain can decode. In the matrix web interface, go to
Device Settings → EDIDand check what is assigned to the relevant input. See
EDID Handshake.
5
Try a different optical cable and amplifier inputRule out the optical cable and the amplifier/receiver input. Connect a known-good optical cable to a different input on the amplifier. If audio is still absent, the issue is upstream of the cable.
6
Reboot the matrixPower cycle the matrix and allow it to fully restart before retesting. If the audio outputs were working previously and stopped without any configuration change, a reboot sometimes clears the condition. If audio returns after a reboot but fails again later, note when it fails and under what conditions — this pattern is useful diagnostic information.
7
Check the error logDownload the full error log from System Health in the web interface. If there are errors related to audio output or HDMI input parsing, these will help support identify the root cause. See
How to Send the Full Error Log.
When It Is a Hardware Fault
If all of the following are true, the audio output section of the matrix may have failed:
- Multiple source devices have been tested — none produce audio on the matrix outputs
- Source devices set to 2-channel PCM — still no audio
- The optical port LED is unlit across all sources
- A different optical cable and amplifier input has been tried
- The matrix has been rebooted — no change
- The fault has persisted for more than two weeks (the issue is not transient)
What to Send to Support
- Matrix serial number and model
- Which outputs are affected — optical, coaxial, or both
- How many source devices have been tested and what format they were set to output
- Whether the optical port LED is lit or unlit
- Whether the fault affects all sources or specific sources only
- When the fault first appeared — was it working previously?
- Whether a reboot was attempted and the result
- Full error log from System Health
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