I used one on vocals in a studio setting and I must say that i was quite impressed with it.
It's a quality piece of gear in my opinion. The most unique feature is the variable impedance control. With that you can tune the sound of the mic.
Class-A tube circuitry. Digital out to 192kHz. High plate voltage option for the tubes. VU-meters.
I don't remember too much about the digital output level control. It wasn't a dsp but some type of analog stage boost just before the converter or something like that.
Extremely good value at $399.