Very basic question if I may to those who have a GISO. Should the ground side be connected to the cable coming from my AirPort Extreme or to the cable going out to my 861?

Main system: NUC, Roon, Network Acoustics Ag ENO/cable, 218, 5200SE, Townsend Podium, Sennheiser HD820/800s, Sennheiser HDVA 820 amp.
Mobile: Explorer, IE800
Kitchen: MS200, F80