My biggest issue with going from USB to firewire were dropouts. I tried the utrends usb to spdif into MF Dac 3 and had dropouts (using J River/flac. vista, asio4all, high performance PC, Cayin A50T and B&W 685 speakers, Nordost cables). I also tried a friends Benchamrk with USB and still had dropouts. The music was good but the dropouts were too annoying. Going to firewire, the dropouts were gone and the music was better, to my ears. I have a better sense of where the instruments are and it seems there is more resolution. The music is close but the dropouts were just killing me. (the lack of dropouts definately effects my perception of the resolution, etc. as I can listen w/o annoyances). I also had my sigmatel soundcards spdif out into dac (sorry, left out all into monarchy dip and than into dac) and the dropouts were nasty. Mind you, these dropouts are probably a millisecond or so but just enough to ruin the listening experience. I have had absolutely no dropouts with firewire. After researching, I attributed the dropouts to USB's packet transmission as opposed to firewire's streaming of data. I am very interested to hear others experience with firewire and usb interfaces. Does anyone get any dropouts?