The secret to Krell's KSA-100S is a technology they've developed called Sustained Plateau Biasing. Essentially, it allows the amplifier to act like a Class-A amplifier but without the inefficiencies of a true Class-A amplifier. The result is a highly listenable, detailed, and nearly magical amplifier for the price. This one has been carefully checked out by our tech and is ready for its new owner. Beware: this amplifier weighs nearly 100 lbs.