You need a tape monitor loop to be able to use an EQ. If you have one (typically 'tape2') you run the outputs of the receiver to the inputs of the EQ and the outputs of the EQ back into the receiver. You then need to engage the tape monitor to hear the effects of the EQ.
If that receiver is new enough to have digital inputs and processing, the EQ probably won't work even if it has a tape monitor loop as it will not direct digital signals to the tape outs. If it is new enough to have digital inputs, it probably does not have a tape monitor loop.