Truth is, no I have not tried to feed the 8000s with a 24/192 signal. In fact, I am not aware of any records with such signals, and even if I did find any I am not sure whether the equipment I have will provide such a signal.
Perhaps I was totally mistaken, but I thought that the special cabling required was internal to the 8000s and not external - hence the request to Meridian to carry out the upgrade if available.