OK looks like this might be sorted!!
On checking, the Airport Express does have a 3.5-mm audio minijack for analog or optical digital sound. I had been using TOSLINK and did not realise that it was analog too. SO .. as the Genelecs ARE powered, all I need is a 3.5mm minijack to RCA phono and I’m off and running.
Not sure what ‘comes out of’ the Airport Express, but here’s hoping that it’s line level.
Thanks all.