This is the latest revision of this amplifier with active cooling, a balanced (XLR) / single-ended (RCA) switch, and a beefier power supply. In amazing condition with perfect front and some minor scratching around speaker terminals on back. The black finish is supposedly harder to find. Includes all manuals and factory boxes for the amp and tubes. *** This amp is available for audition in Lawrence, Kansas *** I performed a minor repair on this amp, replacing two burned up resistors and a small section of trace after a tube went bad and shorted. This is a common issue and I was able to source original parts directly from Audio Research. I am a certified electronic technician and computer engineer who does a lot of audio repair and restoration work, so this was a trivial repair for me. The tubes were tested on my calibrated B&K tube tester and are basically brand new. Bias was set on all 4 matched output tube pairs. The amplifier was then bench tested and listened to extensively. Local Pickup Local pickup and auditions are available in Lawrence, Kansas. Shipping:Amplifier will be shipped in factory box with tubes removed, labeled, and packed separately. Fully insured FedEx ground shipping will be used and additional fragile stickers will be added to outside box. Returns:I dont typically accept returns on heavy audio items like this. I will guarantee the amplifier arrives in the condition stated. I want to make sure you are 100% satisfied. Specifications: Maximum output power: 110Wpc continuous, 20Hz–20kHz at 1kHz with THD typically 0.3% at 110W, 0.03% at 1W; 120W at clipping (20.8dBW).Stereo tubed power amplifier with balanced inputs and 4, 8, and 16 ohm output transformer taps.Tube complement: 4 matched pairs of 6550C output tubes, 4 6H30 driver tubes.Frequency response: 0.6Hz–90kHz, –3dB.Input sensitivity: 1.8V RMS balanced for rated output (24dB balanced gain into 8 ohms).Input impedance: 300k ohms balanced.Output polarity: non-inverting.Damping factor: approximately 12.Hum & noise: 0.2mV RMS, 106dB below rated output (IHF weighted, input shorted).Power requirements: 105–125VAC, 60Hz (210–250VAC, 50Hz), 630W at rated output, 800W maximum, 410W at idle.Dimensions: 19 (483mm) W by 8.75 (222mm) H by 19.5 (495mm) D. Handles extend 1.5 (38mm) forward.Weight: 67.4 lbs (30.7kg) net, 83 lbs (37.8kg) shipping.