[tigersky]

Certainly;

Audio output device                            ALSA: AML-M8AUDIO,PCM
Number of channels                            2.0
Output Configuration                           Best Match
Volume Control Steps                          20
Maintain original volume on downmix   'on'
Stereo upmix                                     'off'
Include LFE in Stereo downmix            0%
Boost center channel when down...      0dB
Resample Quality                               Medium
Threshold for pitch correction              2
Keep Audio device alive                      off
Send low volume noise                       'off'


Allow passthrough                             'on'
Passthrough output device                 ALSA: AML-M8AUDIO,HDMI  (N.B. this line is greyed out and cannot be selected)
Dolby Digital (AC3) capable receiver    'on'
-Enable Dolby digital (AC3) transcoding 'on'
Dolby Digital Plus (E-AC3) capable receiver 'on'
DTS capable receiver                         'on'
True HD capable receiver                   'on'
DTS-HD capable receiver                    'off'  

i guess your avr has only optical in but no hdmi in. HD audio cannot pass through optical out but in hdmi. then why you enabled true hd on. also select hdmi alsa instead of pcm since beelink outputs audio both in hdmi and optical simultaneously even if you select hdmi out. our aim is to get high quality optical 5.1 out rather than the inferior transcoded 5.1 optical out like the android os does for dts audio since it can't be passed through in android os. dts pass through is possiblein linux. that's the beauty of coreelec and libreelec.  

Dear Tigersky

Many thanks for your suggestions.  I have disabled True HD and selected HDMI ALSA instead of ALSA: AML-M8AUDIO,PCM.  Not sure if I noticed difference by Dobly 5.1 and DTS videos still play form all 5 speakers.  Are they playing better quality now? DOlby ATMOS test videos play now sound but that is to be expected as my Samsung home theatre does not support it. 

dear ninja, for HD audios unsupported avrs, kodi will output the core audios to get 5.1 optical out. getting 5.1 out alone is not sufficient . we should try to get maximum bitrate audios to enjoy true surround sound effects .