The Parasound Zphono-USB is a high-quality phono preamplifier engineered for optimum vinyl LP playback quality. The Zphono-USB has precise RIAA equalization and uses high quality parts to achieve extremely low levels of noise and distortion plus accurate frequency response. In the digital realm, the Parasound Zphono-USB has an A-D converter and USB output to make high quality digital recordings of your vinyl LP collection a snap. Its unique front panel USB gain control and USB clipping indicator enable you to optimize the USB record output level to achieve a superior signal-to-noise ratio with most PC or Mac phono recording software. Just select a loud music passage on the LP that you want to record. Turn up the USB Gain knob until the clipping indicator LED turns solid red. Then slowly turn the USB Gain knob down until the clipping indicator never lights up. If you have sophisticated recording software, the rear-panel RIAA defeat switch allows you to defeat the internal hardware-based RIAA equalization in favor of software-based digital RIAA equalization. Two separate power transformers for analog and digital circuits assure the cleanest response and lowest noise. The Parasound Zphono-USB has stereo input jacks for an MC or MM phonograph cartridge. A choice of MM-47 k ohm, MC-47 k ohm or MC-100 ohm enables you to select the ideal gain and impedance for your cartridge.