Hi
I think the sound you're after was Probally created on a Yamaha GX-1.I'm not sure if benny andersson ever owned a CS-80.But the CS-80 should be able to do a very good job of recreating that sound.ABBA's later ablums and the Chess album were dominated by the GX-1.There is no synth that can come close to a GX-1 in terms of sound but with this Cs-80 emulation and my UAD-1 card i'm able to get what i think is close to a few of ABBA's sounds.From what i can hear there is more than one part to that sound i think it must be built up in layers.Are you intrested in his sounds and work?
I hope this helps!
Russell