Go here for parts and updates for each item in your Dynaco stack: https://www.updatemydynaco.com/
So I've built a number of Dynaco kits - SCA-80Q, PAT5, 416, ST70 clone, etc. Started back when I was a starving college student in the early 70's with the SCA-80Q. Built the 416 and PAT5 when living in Amsterdam in the late 70's. My son uses the ST70 & PAT5. I have an FM-5 (factory built, but I've completely restored and aligned it), PAT5, PAT4 (2x), and the 416 - all of which have been restored and upgraded. It all works great - no complaints. I can highly recommend Dan at update-my-dynaco.
I would not recommend switching on the Stereo 400 with a PAT4 preamp. The switch is not rated for the inrush current (one of the reasons Dynaco came out with the PAT5.
Factory wiring was not all that neat. Best ones I ever saw were kits built by great technicians - far better than the factory ones. Time is money...
So I've built a number of Dynaco kits - SCA-80Q, PAT5, 416, ST70 clone, etc. Started back when I was a starving college student in the early 70's with the SCA-80Q. Built the 416 and PAT5 when living in Amsterdam in the late 70's. My son uses the ST70 & PAT5. I have an FM-5 (factory built, but I've completely restored and aligned it), PAT5, PAT4 (2x), and the 416 - all of which have been restored and upgraded. It all works great - no complaints. I can highly recommend Dan at update-my-dynaco.
I would not recommend switching on the Stereo 400 with a PAT4 preamp. The switch is not rated for the inrush current (one of the reasons Dynaco came out with the PAT5.
Factory wiring was not all that neat. Best ones I ever saw were kits built by great technicians - far better than the factory ones. Time is money...