Not sure about the B7K as it is more of a overdrive pedal than a preamp. It has an EQ, but I would personally use it as a pedal thru a preamp such as a Sansamp, Alembic, Monique, etc. YMMV.
In any case.... the first page of their web page says:
With the B7K you will easily create your own signature sound in a huge range of shades from classic warm tube tones, even to scooped ultra high gain distortion. Other great spec of the B7K is the built in DI Output which makes it perfect for live and studio applications. It works perfectly either used as a stand-alone preamp going to a power amp and/or PA system, or to spice up the tone of your favorite amplifier. The Microtubes B7K is a dream come true to get your own signature sound.