The elysia xfilter Mastering Edition is a very sophisticated, handcrafted analog 4-band stereo equalizer, with both channels linked for stereo operation. All four bands provide a precise control range of +/-5dB. The xfilter Mastering Edition produces the high-end sound of a Class A equalizer at an amazing value for the money. This fine analog 4-band stereo equalizer produces an absolutely precise stereo image. This is based on the use of computer-selected components with extremely low tolerances.