I had tried one of these last year and was not impressed with it, compared to a Presonus Dual Bluetube preamp and sent it back.    I just got another one, and apparently an updated version, and this one is an improvement.  Tests with a female singer (my wife) in comparisions to the Bluetube and direct into my Octa-Capture are both much better.   This one is a "keeper".
 
I don't know what the difference is in this later production model, but it does have some Burr Brown OPA2134 Op Amps and that was one of the items in several user "mods" that I saw for this unit.
 
 
Jack