@Kota1 thank you, asked them. I hope McIntosh is as kind to me as they have been to you.
@mahler123, this unit does not have an ethernet connection but has a USB2.0 port - a $15 usb to ethernet adapter compensates for the lack of ethernet port although it is for music streaming, not firmware. I did notice there is another mini USB port snuck underneath the unit. Given its relative inaccessibility and proximity to the middle of motherboard it appears to be dedicated for firmware uploads.