If you have the proper Meridian speaker cable with audio (phono) and comms (din) on same cable I would not bother with BNC comms and use the far more common DIN comms from the M5/C5 leads instead.

You will find the 2 DIN sockets in the top middle rear of the G68D.

[Linked Image from Meridian-audio.info]

Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).