Trace the intended audio destination
Note whether the goal is sound from the Mac’s built-in speakers or from an HDMI-connected audio receiver. Keep the Mac model and any USB-C-to-HDMI adapter with the connection description. A visible external picture alone does not identify where the programme audio should be decoded.
Apple documents passthrough for supported Dolby bitstreams on an Apple-silicon Mac using its built-in HDMI port or a supported adapter. This is a narrower feature than ordinary stereo playback and should not be assumed to cover every encoded format, Mac generation or wireless speaker.
Compare the player preference with system output
QuickTime’s playback guide places Prefer Passthrough under View, Audio. Apple directs users of built-in speakers to turn it off. For an HDMI receiver and supported Dolby audio, its Mac guide says to enable the preference and select the HDMI device in sound output settings.
Record both selections before a comparison. Apple also notes that additional audio output while HDMI passthrough is used follows the previous sound-output setting. A system sound from one speaker therefore does not by itself establish the programme’s passthrough destination or show that the player ignored its selected receiver.
Compare the same permitted audio track
Use the same file and audio track while changing only the intended routing preference. Check the receiver’s displayed format as well as the audible result. A different title or track can introduce another explanation for changed sound, even when the external picture remains identical.
For help, provide the Mac model, operating system, player preference, system output, adapter and source audio format. Keep built-in speaker and HDMI-receiver results separate. These details distinguish an output-selection issue from an unsupported passthrough path and prevent a working system-alert sound from being mistaken for proof that a separate encoded programme route succeeded.