This is a really nice power amp ! From a non smoking home. Very clean and working perfectly. Here is a video of the amp working (pre amp in video is not included) https://youtu.be/PuTWK4s3Oa0 From the manual: The ST2140 utilizes high quality electronic circuitry to achieve an environment wherein a detailed, transparent, and highly musical sound can be realized. The high quality parts complement include state-of-the-art solid state devices, 1% metal film resistors, computer grade electrolytic power supply capacitors, and a high capacity toroidal transformer. The ST2140 operates class A predriver and AB high current MOSFET power output stages. It is capable of reproducing the most demanding audio signals at rated power levels. Features Toroidal Transformers - Efficient high current transformer for improved dynamics. Discrete Circuitry - More accurate and three dimensional reproduction of source material. Class A Predriver - Improves low level detail for smoother, more musical sound. AB MOSFET Output Stage - For efficient and linear power delivery. Limited Protection - Provides short term protection from accidental shorting of output devices and protection from thermal overload. Gold Plated Connectors - Improve connections for better sound and minimized signal loss and degradation. 1% Metal Film Resistors - Low noise resistors for better sound and a greater degree of repeatability. High Current - Ability to reproduce demanding recordings. Computer Grade Capacitors - Large capacity computer grade electrolytic capacitors for extended low frequency control and improved dynamics. ST2140 SPECIFICATIONS: Power rating: 8 ohms 140 watts @ 1 kHz / 4 ohms 185 watts @ 1 kHz Frequency response: 5 Hz - 45 kHz Input sensitivity: 1.2 Volts THD (S+N): 0.09 % @ 1 kHz Input impedance: 33.2 k ohms Damping factor: 100 Current (peak to peak): 30 Amps Slew rate: 14 V / sec Dynamic headroom: 1.4 dB S/N (A-weighted): 95 dB Voltage gain: 28 Line voltage: 120/220/240 VAC switchable Dimensions: (O.A.) 17(w) X 15.5(d) X 5.75(h) Weight: 31 lbs Power consumption: 450 watts max / 4.6 Amps max current draw / 40 watts @ no input Replacement fuses: Line - 8 Amp/250 Volt Slow Blow / Rails - 4 Amp/250 Volt Slow Blow