Help looking for information

Hi there I am looking to buy a vintage CR system but I am wondering what is the difference between the CR-xx20 and the CR-xx40? Are there certain models I should stay away from? I'm not looking for a system that will shake my house or anything though I do truly like the look of the 1020. any advise would be awesome and if anybody has a unit for sale please PM me.

Cheers Erich

CR-1020,2020,3020 or 2040 would be my choices. Amplifiers are all discreet components.