The CSA100 integrated amplifier is a part of the latest work by Copland, aiming to combine the advantages of tubes and transistor amplification using the synectic design concept that previously has made Copland hybrid amplifiers widely acclaimed.
One tube is responsible for the CSA100 line amplification and the efficiency of this single tube layout is astonishing. The double triode tube runs at high voltage in a setup for maximum linearity, taking care of the voltage amplification only.
A MOS-FET circuitry delivers the brute force driving the line stage output and feedback circuitry, thus securing a firm handshake between the world of electronic tubes governed by voltage and the current controlled transistor technology.
If you prefer the warm and nice colored charm of some older tube designs look elsewhere, the CSA100 tube line stage is made for monitoring. In this application the tube provides life, headroom and dynamics hard to find in amplifiers relying on solid stage technology only.