The EC/SE is a deluxe production version of the classic Ampex 350 amplifier circuit with added features. 6SJ7 and 6F6 Metal Pentode Tubes, Select Input and Output Transformers, 70dB of gain, a DI input, a proper Single Ended Output Stage, the absolute finest Mil-Spec Resistors and Boutique/NOS Capacitors, and a full complement of Input and Output Attenuation make this unit a must have for the modern recordist. The EC/SE has a wonderful response and a sweet tone.