I’m happy to answer questions and provide further information. My setup is…
Two pi3s both controlled via orangesqueeze:
Usb hard drive (for music)
HDMI connection to TV and it’s sound bar.
Max2play os. (DigiAmp+ still available in settings)
Client to squeezebox on Pi3 One.
I switched the Pi’s around and it worked.
Noticed after that that there were ‚goings on‘ with cross fade function in orangesqueeze /squeezebox and removed the cross fade between tracks which cleared the problem.