Simply put, the REF150 SE is a breakthrough in stereo power amplification. Replacing the REF150â€”which was one of the most respected modern stereo amplifiersâ€”was a daunting task, but it has been accomplished. The REF150 SE offers more power, greater dynamic thrust, a more vivid and resolved presentation, greater finesse, and quieter operation. It is the new benchmark. Having identical outer dimensions as its predecessor, the REF150 SE has much more packed into its chassis. Refined front-panel cosmetics reflect the updated look of current-generation models, with silver units having silver handles and silver top covers, while black units have black handles and black cover. (Colors may be mixed to match older models.) The REF150 SE is a fully-balanced design, so its inputs are balanced XLR only. It has a 20-amp IEC power connector, 4-8-16 ohm output taps and 12V triggers arrayed on the rear panel. Under the top cover there are a number of circuit enhancements resulting in stunningly improved performance. First, power-supply energy storage has been doubled to some 1040 joules. All-new interstage coupling capacitors using technology and materials first incorporated in our Anniversary Edition preamplifier effortlessly link input stage to output stage, which is powered by two matched quads of Russian KT150 output tubes driven by 6H30 twin triodes. There is more than ample multistage solid-state regulation. Output stage coupling is a combination of â€śultralinearâ€ť and Audio Researchâ€™s patented â€śpartially cathode-coupledâ€ť topology, which is superior to conventional pentode or triode operation. Larger, wide-bandwidth output transformers handle the greater output with ease. Power output is rated at 150 WPC into 4-, 8- or 16-ohm speaker loads. Each channel is very quietly fan-cooled using new low-turbulence intakes, with three selectable fan speeds. Internally there is a small LCD display that indicates tube hours. With all of these changes one would logically expect enhanced performance. But it is fair to say you will be shocked by the amount of improvement you hear from the REF150 SE when compared to its predecessor. Those familiar with the boundary-extending performance of the Anniversary Preamplifier will hear similar qualities from the REF150 SE. The immediate impression conveys much greater speed, power and control compared to any other tube power amplifier you can think of. Bass extension, harmonic delineation and speaker driver control are the best ever to come from an Audio Research tube amplifier, regardless of power output â€“ and that is saying something. The REF150 SE does not drive a loudspeaker so much as it dominates it and brings to life what any speaker is truly capable of. Paired with capable front-end components and good cabling, the results are nothing short of a revelation. You will hear inner harmonic structure and dynamic realism that simply were not present before, within an envelope of air and spatial cues that let you know that you are hearing everything that the recording has to offer. In short, the REF150 SE amplifies more critical musical information from your preamplifier and source components than you have ever heard before. Prepare to be astonished once again.