You could use a powerlink / DIN to RCA cable to do this job.
Check with steve at http://soundsheavenly.co.uk/default.htm
Or get a MCL 2P ampflifiert to connect to the ouverture and attach you passive speakers to this one: http://www.beoworld.org/prod_details.asp?pid=979
Ralf
My Beo: Beosound 3000, Beolab 4000, Beo 4 DVD, Beolab 5000/Beomaster 5000, Beovox S45.2 with Stands, Beosystem 7000 black with Beolink 7000, Beolink 1000, F1000 (3 cubes), Beovox 5000, Beovox 3000, Attyca 1.