Quite possibly the most beautiful amplifiers ever designed.Utilizing KT150 tubes, this is about as modern and detailed sounding a tube amp will get.Both amps look practically new with JUST 325.6 hours on the tubes which is the same amount of hours in two weeks! And we know such an exact figure as ARC displays this right on the rear. We wish more tube amplifiers had this feature, as it's one of the most asked questions. Built-in auto bias means you never have to fuss around with the tubes. And tube rollers can play around with KT88, KT120, and 6550's without making any adjustments.And this listing comes to you complete with all of the original Audio Research packaging and originally included materials.