The Fosi Audio Phono Preamp Box X2 eliminates low-frequency noise and ensures clear sound quality by converting phono signals into line-level signals using high-quality components and low-noise integrated circuits. Thanks to the built-in grounding connection, your turntable is reliably protected. High compatibility and customizable control are provided through adjustable gain levels. You can switch between 3 modes: 39, 42, or 45 dB. Only high-quality components were used in the construction and assembly of this phono preamp, allowing you to enjoy a very warm and smooth sound. The compatible vacuum tube models include 6K4, 6J1, 6J4, GE5654, 6AK5, 66, and more. To make changes yourself, simply swap out the vacuum tubes, keeping in mind that different tubes produce distinct sounds.