It might be worth a check that the G91 is running later FW as the earliest FW was reported to have poor idea quality. I've not tried to do anything unusual (such as long cables) but I haven't found the G98 or G91 cable sensitive when I've used the HDMI output.

Regards

Richard

Main system; 861v8 ID41, DSP8000SEU fronts with DSP5500 centre and DSP7000 rears (all in lovely silver) 504, HD621
Second system 861v4 ID40 LPS, G98DH, 504, HD621, 2x DSP5200 with DSP5200 centre
MD600 tucked away in study. Lots of other Meridian!