Absolutely superb! I have one of the first RME Fireface UC interfaces that arrived in the US and have not looked at anything else since. It continues to perform flawlessly in every capacity. The kicker, it's only a half rack space.
I've had my Fireface UC for about three months now, and am very pleased. I had an issue initially with it playing back sound FASTER than it should, but this turned out to be an issue with Windows 7 Audio Enhancements being turned on, and caused similar problems with other non-RME interfaces. Sweetwater's tech support and my Sweeterwater sales rep were excellent in helping me with the issue.
There's a noticeable improvement in sound quality over the PreSonus Firepod interface I was using prior. Input signals have a lot more gain then I used to have, and the inputs sound great. I'm very pleased. Would have been nicer if it wasn't so expensive, though!
Finally, an interface that just works
I have been using firewire interfaces for years, but they don't function predictably on modern windows laptops. This unit is fully functional on every computer I hook it to. Win 7, Vista 64, XP, various laptop manufacturers. The preamps sound awesome and the amount of in/out options is incredible like the instrument ins can be switched to line level ins. The software is very intuitive and simple to use, and the latency is very low (2ms or 48 samples) if you want to play with soft synths/drum samplers. You also have the option of routing the input directly to the phones for zero latency.
Sounds great; very low noise floor; plenty of I/O options. Low latency performance is very good for a USB system.
The supporting software is reliable and has a nice polished UI.
Overall a very professional package. 4.5 stars only due to the premium pricing.
Amazing USB Interface
I just upgraded from an Apogee Duet2 to the Fireface UC. Wow, what a difference, especially when using spidf into the Fireface. The physical build is solid (German engineering gets a 10 out of 10 here) and the sound is excellent. Converters seem to be at least as good as Apogee's, if not better. The new TotalMix FX software is very good, but takes longer to learn than the Apogee software (the manual isn't updated for the latest FX version which caused me to lose a few hours). But the software is also 100x more powerful. There are so many inputs and outputs that can be connected in any configuration. You can mix any inputs to any outputs. All in a compact 1/2 rack box. Firmware upgrade and driver install were EASY on a Mac Pro! I rated this 4.5 and not 5.0, only because RME needs to do a better job writing their manual and making the software a more intuitive. You will not be disappointed with this interface!