Second knob from the left has the SQ and RM decoder selection, It does have the decoder built in.The design is interesting and yess joystick Quad balance control is awesome. I like the way they store surround speakers inside the main ones making it a dual amp stereo system.
It's probably average quality for the time.
I don't see if there is a quad decoder built in for the PE turntable.
I would built a smaller component cabinet and get rid of this bulky one.