The Classe' CA series amplifiers have a poorly designed power button "de-bounce" circuit in my opinion. Most amplifiers today have a microcontroller interface for the power-on sequence. This amplifier uses an RC circuit to create a pulse to clock a flip-flop and is unreliable. I had listed this amplifier earlier with this issue but pulled the listing as it became very frustrating when it refused to powerup. I replaced the push button, flip-fop and RC filter components and was not satisfied that it would be reliable. I decided to build a schmidt trigger circuit to create a solid pulse. See photo of scope traces. The top trace is the signal after the modification. The bottom trace is the original signal. Note the glitch at the beginning of the bottom trace. This glitch is what causes the issue. My modification is the small board mounted to the existing handle mount. This modification does not have any effect on the audio performance and is 100% reversable. No traces or wires were cut or any drilling was done. The RC filter Cap and resistor C10 and R9 were moved from the Classe (bottom board) to my mod board and are wired in front of the schmidt trigger circuit (see schematic photo) as C1 and R8. Because of the way this amplifier is assembled, it is extremely difficult to work on as this circuitry is on the bottom board and is very inaccessible. It may have been okay after replacing the original components but due to the accessibility problem I didn't want to risk it. Any other Classe CA series amplifier may have power-on issues as described.