The CTA506 power plant is based on the KT120 power valves. These valves are a new variant of the legendary 6550 / KT88. For more than half a century, the classic KT88 valves have been the foundation of numerous of high quality amplifiers and surely, they will continue to serve as one of the premium choices among manufactures of high-power valve amplifiers. However, nowadays KT120 is one of the most powerful dedicated audio tube in production. In comparison with the KT88, nearly 30% more power can be drawn from these remarkable valves. With a plate dissipation rating of 60W, a pair of KT120 valves in push-pull configuration can deliver nearly 200W of audio power. When used in circuit designs of more modest power outputs, the KT120 can deliver incredible quantity of headroom and dynamic without overloading.