Originally Posted by GREMeZ
Thank you for your reply
Steps were made so far:
- attempt to reduce number of channels from 7.1.4 down to 2.0
- microprocessor reinitialisation
- reset to factory firmware FW 2101-5133-8132-4054 (DTS 3.90.35.00)
It seems "defective DTS decoder" is the most likely case
Modern AVRs don't have a separate "DTS decoder" that can go bad. Vanilla DTS (not necessarily the various artificial enhancers which may use proprietary chips) and Vanilla DD are typically handled by the same OEM DSP chip and the decoding is part of the chip firmware programming (i.e., no separate hardware areas). So one of them is unlikely to "go bad". This decoding is done as early as possible and rest of the hardware is common to both.
Also, if the audio is able to play for a while and then starts distorting or goes silent, it is typically not a decoder (or a hardware) problem but a buffering and/or resampling issue in the digital path, typically with non-dedicated audio equipment.
To narrow down the problem you have to simplify your set up to the smallest configuration possible that can display the issue, not juggle 3 or 4 different combination of sources each with multiple options on how the audio is processed and make arbitrary guesses as to what is going wrong. You are likely to make bad guesses based on correlation than cause.
In your case, the simplest would be to eliminate Plex and Xbox and use Kodi on your Nvidia Shield playing two local (or on USB) files, one with DTS audio and one with DD (not DD+). First, go to Kodi Audio options and set everything to default. Then enable Pass through and make sure that both DD (AC3) and DTS capabilities (receiver capable) are checked. It is also better if both source files use the same sampling rate (preferably 44.1 or 48). Also get DD and DTS samples from different sources (demo videos on YouTube are the best bet, not various pirated media one can play through Kodi which can have bad processing). Its is also useful to select the sources so that both have 2.0 or both have the same multi-channel recording.
Now, switch the AVR to direct mode and play the two files and make sure that the OSD or app status display of the AVR shows DD or DTS for the input.
Now see if you can reproduce the problem.
If the problem occurs, in the Kodi audio options, turn off passthrough. Do the same test (AVR should just say PCM for both not DD or DTS in this step). Does the problem occur again for the two sources?
Next try enabling Passthrough but toggle DD and DTS capable options individually so that one is off and one is on (two separate tests).
Or if you have a DVD/BR player, the most reliable test would be to play legit, original (not ripped or cloned) discs one with DTS and another with DD audio connected to the AVR with audio on the player set to passthrough (so that AVR is showing DD or DTS on its inputs not PCM). These have less options than the Xbox. Or you can play the discs through the Xbox and skip Kodi/Plex.
Also make sure that both formats go through the same cable to the AVR (HDMI or Optical). If you have options between the two, try switching between them.
Gather some info on the above tests and post them and perhaps that will lead to better diagnosis.