I hooked Zone 3 up to an Acoustic Energy Aego subwoofer and satellites in another room and maybe I shouldn't expect better given the difference in quality of kit to the G68, but found a hum turning the volume up to very high levels without music that is not evident playing music at normal listening levels. The noise is not evident when I disconnect the interconnects from the G68

Appreciate any advice on whether this is likely to be a cable shielding (10 meter cables) or a ground loop problem (I always thought they were more severe) and if and how I might try to eliminate it.