If anyone is still interested in this thread, I can say that the M2Tech was a huge improvement in sound from PC optical out to DAC. After living with the HiFace for a year, I upgraded to the Anedio U2 USB interface. It was a major improvement in overall presentation. In fact, I was so happy with the U2 that I pre-ordered their new DAC2 and am planning to eliminate another "box" and go straight from the PC via USB to the DAC2.
Hope that helps.
Hope that helps.