I think USB plugs vary slightly in width from manufacturer to manufacturer so it partially depends on what you're plugging into the USB port. The only way you're going to be absolutely safe is to plug in the USB cable you'll be using and measure from the widest edge of the plug to the center of the S/PDIF input and find a cable with a plug that has a radius no larger than that. (Or, better, take the MT in to the store with you along with the USB cable and test the S/PDIF plug there.)
Craig