well basically the preamp is to make your sound studio quality.. u hook the mic in it and there is no static.they also control the levels for evrything plugged into it. sounds comlicated but when u get it its really simple. i have the lexicon omega.. hook the mic nto the omega.. crispy clear sound.. theres like 8 knobs on the front , it can control the volume of 2 mic. headphones, ur monitors. an instrument or whatver. but if u only have 1 mic and evrything.. u really just need the lexicon alpha