Cambridge Audio 551P The black Cambridge Audio Azur 551P Moving Magnet (MM) Phono Preamplifier is a phono pre-amp.Most hi-fi amplifiers wont let you plug in a turntable directly. You need to connect via a phono stage (also known as a phono preamp) to make the very quiet signal from the turntable powerful enough for your main amp to work with. But its very easy to add noise at this stage, which is why the 551P amplifies the signal without distorting it or introducing noise.This phono stage is a Moving-Magnet-type (MM) phono stage, which describes the commonly used type of cartridge configuration typically supplied with affordable modern turntables.The 551P works with all popular turntables that use a Moving Magnet cartridge (the stylus or needle).Phono preamplifier with moving magnet (MM) input stageAcoustically damped full-metal chassis with thick, brushed-aluminum front panelDiscrete transistors for the all-important input stages instead of the more common integrated circuitsSingle-ended, Class A gain stage with audiophile passive RIAA equalization