Fully functional. Potentiometer switches all functional as well as lights. 4-channel sound without noises and crackles. Two phono inputs great for vinyl lovers. Optically with minor scratches on the front and cover. See pictures. The 4VN-880 integrated amplifier features a 3 stage direct coupled equaliser circuit and NF type tone control. The use of BTL connection enables the amplifier to double its power when it is used as a 2-channel amplifier. In the first stage of the main amplifier there is a phase reversing circuit which reverses the phases of the input signals. The original input signals go to the CH-1 and CH-3 amplifiers and the reversed phase signals go to the CH-2 and CH-4 amplifiers. At output the signals are composed giving an output theoretically 4 times greater than in 4-channel playback. Specifications Power output: 55W/ch into 8Ω (stereo), 25W/ch into 8Ω (quadraphonic) Frequency response: 20Hz to 50kHz Total harmonic distortion: 0.5% Damping factor: 50 Input sensitivity: 2mV (MM), 100mV (line) Signal to noise ratio: 65dB (MM), 75dB (line) Output: 100mV (line), 30mV (DIN) Speaker load impedance: 4Ω to 16Ω Dimensions: 138 x 420 x 362mm Weight: 12kg