Thank you blgentry, Spike1000, and swiv3d for your helpful advice.
Spike1000, your tutorials are splendid and a great service to this community.
From your combined comments, I realised I needed to start all over.
I uninstalled MC24 and reinstalled it.
I'll repeat my set-up for good order's sake:
MC24 installed on ZenBook Pro wirelessly connected to cable router on home network.
I am using OPPO BDP 105D as DAC that is connected to said router via ethernet cable. Optical cable from the OPPO to Thule amplifier.
(Numbers below against each description signify attachment number
The OPPO is listed under Playing Now - 1
Enabled DLNA under Media Network -2
In the Player zone options to change are available -3
However, in the BDP - 105D zone I am directed to Media Network>Add or configure DLNA Servers... and cannot set any output formats -4
Under DLNA Servers I have chosen Audiophile 24 bit DAC and PCM 24 bit -5
Finally in the File view you can see that I am in the OPPO zone and can play the files -6
The thing is: 1)The sound problem remains 2) I cannot pause or stop mid track.
If it helps these are the audio specs of the OPPO BDP 105D
Output
Analog Audio: 7.1ch, 5.1ch, stereo.
Dedicated Stereo Analog Audio: XLR balanced, RCA single-ended.
Coaxial/Optical Audio: up to 2ch/192kHz PCM, Dolby Digital, DTS.
HDMI Audio: up to 7.1ch/192kHz PCM, up to 5.1ch DSD, Dolby Digital, Dolby Digital Plus, Dolby TrueHD, DTS, DTS-HD High Resolution, DTS-HD Master Audio.
Input
HDMI Audio: up to 5.1ch/192kHz or 7.1ch/96kHz PCM, Dolby Digital, Dolby Digital Plus, DTS, AAC.
MHL Audio: up to 5.1ch/192kHz PCM, Dolby Digital, Dolby Digital Plus, DTS.
USB Audio: up to 2ch/192kHz PCM.
Coaxial/Optical Audio: up to 2ch/96kHz PCM, Dolby Digital, DTS, AAC.
Many thanks