Any audio decoding/conversion/processing by the TV introduces massive audio lag, and that's likely due to lack of sufficient computing horsepower inside the TV, so it's unlikely to be fixed by any firmware update.
The magic feature you need to enable and use is "Pass-through" mode (as opposed to "PCM" or "Bitstream"). Sadly, these TVs are not spec'd to pass-through audio over the optical port; the best they can do is decode-and-reencode the audio to produce it on the optical output. To achieve "Pass-through" mode, you MUST use eARC... but very few customers at this time have sound bars or AV receivers that support eARC. Most of us have devices that only support the older (and incompatible) ARC protocol, or that only support non-eARC HDMI or digital optical inputs.
And, due to a firmware bug in the entire 2020 series of Samsung TVs, they also will not pass through uncompressed 5.1 or 7.1 LPCM (aka PCM), even over eARC, and will instead downgrade such signals to 2CH (stereo) uncompressed LPCM (aka PCM), so you have to be willing to use encoded formats such as Dolby Digital or Dolby Atmos to make all of this work.
The only solutions to this predicament are:
- Use optical out directly from the device (game console, PC, whatever) directly into the sound bar or AV receiver (thus bypassing the TV entirely).
- Use an AV receiver (with built-in eARC support) connected to HDMI3(eARC), with the source device set to output "Dolby Digital" or "Dolby Atmos" (whichever your sound bar or AV receiver actually knows how to decode), with the TV set to use "HDMI-eARC" audio output in "Pass-through" mode.
- Use a Thenaudio.com SHARC as an eARC audio device connected to HDMI3(eARC), with the source device set to output "Dolby Digital" or "Dolby Atmos" (whichever your sound bar or AV receiver actually knows how to decode), with the TV set to use "HDMI-eARC" audio output in "Pass-through" mode. The SHARC provides digital optical output and non-ARC non-eARC HDMI audio output that you can feed into almost any old sound bar or AV receiver -- and it converts so quickly that no audio lag or lip-sync problems can be observed.
I own a Thenaudio.com SHARC and can confirm it works perfectly with my Samsung Q90T to finally provide lag-free Dolby Digital audio to my old non-Atmos non-eARC Yamaha AV receiver. It was the ONLY "universal" way for me to achieve this across ALL the different devices (many of which do not provide separate optical digital audio outputs) that I use with my system.
One other IMPORTANT CATCH to be aware of:
The TV utterly relies upon HDMI pins 13 (CEC), 15 (DDC clock), 16 (DDC data), and 19 (hotswap detect) to detect and initialize any eARC audio device... but some devices are poorly-behaved and erroneously hard-wire one or more of these HDMI pins to ground (especially when the device is turned off). If such a device is wired into your system anywhere -- even into a separate input port on the TV or AV receiver, or even into an HDMI switch in the signal path before the TV -- then the TV will fail to pop up its little "audio device detected" text or to show "HDMI-eARC" as an available audio output device in its menus. If you plug in a SHARC or other eARC device and the TV doesn't obviously detect it, then you may still hear audio out over the eARC device, but the TV will not show "HDMI-eARC" as the audio output device, nor will it allow you to select the oh-so-critical "Pass-through" option in its menu. In this case, you should unplug ALL other HDMI devices from your system, then unplug and re-plug the eARC device into HDMI3(eARC), then wait several seconds and see if the TV says it has detected the device. With no other devices connected to the system, that should work. Then, attach one more device, and unplug/replug the eARC device from HDMI3(eARC) again, and see if the TV detects it. Keep going through this process, adding back one device at a time, until you determine which one is responsible for preventing the TV from detecting the eARC device. Once you've identified the bad device, you'll have to leave that device's HDMI unplugged at all times unless you are using it.
