Control what the source is told.
Start by isolating the variable.
The user manual documents EDID audio controls for LPCM and formats including Dolby Digital, Dolby Digital Plus, Dolby TrueHD, DTS and DTS-HD. This makes it possible to test how the source reacts to a known audio capability set.
What DR HDMI 8K can — and cannot — tell you
An EDID can advertise support; it cannot add a decoder to a TV, soundbar or AVR that does not actually support the format. The complete playback chain still has to support the requested audio mode.
Important: For Apple TV 4K, use the dedicated guide as well: the manual contains Apple TV-specific troubleshooting notes.
A practical test order
- Confirm the source, display/AVR and cable support the target format.
- Start with a known working lower-bandwidth mode.
- Read or copy the downstream EDID.
- Present a known predefined or deliberately modified EDID to the source.
- Change one capability at a time and observe the result.
This approach is more useful than changing the source, cable, AVR settings and EDID simultaneously because it keeps the test repeatable.