The Triode 25 was born out of the huge success of the long-standing Triode 20 amplifier and released as part of the 25th anniversary celebrations of Unison Researchs formation. Its been developed over an extended period to ensure it is a worthy successor to the Triode 20s name. Like its predecessor the Triode 25 is a push-pull amplifier that utilizes EL34 tubes in the output stage. The push-pull circuit includes a final stage with two power tubes intended for the amplification of the audio signal and is then followed by a symmetrical output transformer stage that reconstructs the signal into a high-quality linear wave.