Paul White of Sound On Sound magazine reviewed the DGT 650 USB microphone and interface in a very informative way.
Summary: "USB mics aren’t always taken seriously, but this one looks every bit as professional as LEWITT’s mainstream studio mics.
The audio quality from the mic is very clean, with naturally airy highs and no obvious added ‘character’, which is probably a good thing for a mic that will be used with both voice and instruments. The controls are easy to use and operation is largely intuitive.
Having both mono and stereo modes is very useful if you want to use the mic to capture a live performance, and I also have to say that this is the first time I’ve come across a MIDI port built into a USB mic. On my Mac this was, again, just a case of plug in and play. The mic-plus-line mode is very handy for guitar and vocal recordings, as the line-input impedance is high enough for the direct connection of an electric guitar."
Conclusion: "Overall, then, I have to conclude that LEWITT have managed to cram rather a lot into this microphone, but they have done it in great style. The build quality matches that of their premium studio mics, and the audio quality makes the DGT 650 suitable for studio use as well as podcasting, location sound gathering and recording your gigs.
There’s the option of using the mic in stereo, and the instrument input is handy for guitar players and suchlike, while the MIDI input is perfect for those musicians who have an old-school MIDI controller keyboard or MIDI guitar system without a direct USB MIDI connection option. Furthermore, for iOS users LEWITT have a free recording app you can use with the mic. LEWITT call the DGT 650 a USB multi-tool, and I think that pretty much nails it!"