I just bought the Musical Fidelity V Link and got it two days ago. I have tried it on some music that I purchased via itunes piano recordings that sounded particularly harsh in the treble via USB (source--MacBook Pro) and it has completely ameliorated that problem. Too early to make other judgements but if it makes itunes more listenable then I consider it worth the $170 that I paid.
USB to SPDIF Converters
There are many on the market now.I have a Hag USB .I would like to hear your experiences with these devices.I would like to upgrade soon,to include Hi Rez downloads ,which means getting a different DAC and converter .