Level/Depth on DJM 850K

Hi everyone,

I was wondering of someone could enlighten me about the following: I am having this DJM 850K and, whilst inactive, when turning the Level/Depth knob all the way to the right, an effect (up echo for instance) could still be heard. Its soft and fades away though, but the fact to matter is that it creates an effect whilst the on/off button is switched to off.

Could it be that there is still some current left or something? I mean, when turning the knob again, no effect could be heard.

I hope someone recognizes this and thus could tell what is happening here.

Thank you already in advance.