The Burl B1D is the same as the B1 except that it has an all iron BX4 output transformer giving it a more terrifying rock tone. Single channel mic pre for 500-series.
An all discrete transistor, class-A, direct coupled, capacitor free circuit path, gives the B1D amazing punch on drums, beautiful tonality on guitars, and warmth with presence on vocals.
The B1D come complete with both Gain and Level controls. If you want that heavy, gainy tone, crank up the stepped gain control and offset that with the level control. If clean tone is your thing, turn the gain down and crank up the level. For ribbon mics and other low impedance sources, the B1 has a transformer coupled impedance select. It was rigorously tested with the popular Royer R-121 in the low impedance setting. The B1 gets the best out of any microphone, whether it be dynamic, condenser or ribbon.
Use the B1's 1/4" instrument/line input on the front panel, plug in, crank up the gain and go. The PAD switch allows for hot signals and balanced line inputs through the mic XLR on the back panel. Run your tracks or mixes through the B1 for warmth and glue. The B1D was designed to rock. Run multiple B1 channels for your rhythm tracks and you are there. Replace EQ and compression with true analog PHAT. Run your primary tracks through the B1 mic pre, follow with a B2 Bomber ADC and that's about all you will need.