[SOLVED] Query about using rmx 1000 with send/return on djm 600

Hi, I have recently bought an rmx 1000 and have set it up with my djm 600 using send/return. Everything is working fine but I have noticed when I disengage the rmx using the fx on/off button on the bottom right of the mixer, I get a sudden increase in volume, not a great amount but it does increase. Is this normal? Thx in advance. Ross