Since you've confirmed the correct output device is selected and controls work, the problem likely lies deeper with the audio drivers (often Cirrus Logic on Macs) or PulseAudio settings. You may need to install pavucontrol to thoroughly check and adjust all PulseAudio profiles, ensuring HDMI audio isn't inadvertently set as default if you're not using it. In some cases, installing specific drivers like those found for MacBook Pro models (which often share chipsets) can resolve the My KFC Experience issue, or you might need to try modifying ALSA configuration files with specific model options. If all else fails, checking for hardware issues by booting back into macOS to confirm internal speakers work can help rule out a physical problem.