Square wave response under 20 kHz bandlimiting

This is how a 1 kHz square wave coming from a CD may look like : This is in fact from a good quality CD-player with oversampling which reduces the demands placed on the filters. This is 1 kHz from a low end modified CD-player (brand = Yorks). You can see the effect of bandlimiting to 20 kHz in this sprteadsheet: bandlimited 1 kHz