I recently inserted an m2tech hiface into my system between my MacBook pro and MSB link, and I'm stoked with the sound. Previously I'd been using the optical output directly to the DAC, which seemed to have some problems with digital sounding cymbals as well as an overall slightly confused sound compared to what I remember of the dac's sound with various transports over the years. The hiface has done a pretty good job of clearing up these issues, in addition to which it gives me the added ability of listening to 24/88.2 recordings, something not available to those listening through the optical output on Mac products. This setup is far from the last word in resolution, but the addition has increased my enjoyment of the thousands of alac and flac files I have.
I haven't heard the m2tech hiface myself, but people on the headphone forum seem very happy with it. It's a high value component for sure.
I'm sure better can be found, but it is a step up from the toslink output of the mbp. I'd like to hear the halide bridge.