"The dBooster has two gain settings, 12 dB and 20 dB, allowing you to dial in just the right amount of in-line gain for your different singers and instruments. The 20 dB setting gives loads of clean boost for recording soft instruments and singers, but when your singer is wailing or you use the dBooster on high volume instruments like electric guitar, switch it down to 12 dB to keep from overloading your preamp or digital interface" - Royer Labs