Focurite 18i8 Problem

I have just had to replace my Edirol FA66 that has been bullet proof for nearly 20 years - the audio breaks up after running for about a minute. I had 2 sets of active speakers attached - one via the digital out connection.
I have the Focusrite 18i8 (3rd Gen) connected and the speakers connected to the main analogue output work fine but I cannot get the speakers connected to the S/PDIF output to work at all. I have the drivers installed and have tried to configure this in the Focusrite Control app and setting up the Midi Audio app on the Mac but to no avail.
Has anybody been successful with this? Am I missing something obvious?

Thanks in advance,

Nigel

What kind of mac is it? I ask because sometimes there are problems with the M1/2 macs and audio interfaces, usually Intel macs are easier to sort out. It would also be good to know what hardware you have between the SPDIF output and the speakers (if any), and what speakers you have. I recommend you call focusrite and get them to help you configure the SPDIF output, as it can be complicated and it's usually not intuitive! Every manufacturer seems to go about it their own way.

Thanks for your response; and I'm happy to hear you say that the setup isn't intuitive - I thought I was just being stupid. I use an Intel Mac mini and as the speakers are active, I'm just using a cable between the Focusrite and the speakers. I have just ordered a new cable to see if that is part of the problem - trying the cheap fixes first.

Ah, should be an easy fix then. What's tricky about SPDIF is that it has to be configured correctly. For instance, sample rate has to match at source and on the speakers. If you're using fibre optic, make sure the cables and connectors are clean! It's worth trying a new cable though, but also make sure the sample rates match!