One more thing, just based on the empirical evidence that is out there, if the type and quality of the interface were unimportant, why do Wadia, Theta, Audio Note and other high-end DAC makers consider it in their designs? For example, Wadia and Audionote devote most of their digital inputs to either glass toslink or coax. I would have to assume that the guys who are at the cutting edge of digital music reproduction would not place much emphasis on the interface if it did not have an impact on performance.