Queston On Burning In A New Preamp

This is a good question for an AI. I believe that the answer is that the amp does not need to be on. I'm in process of doing the same thing with a tube phono stage to burn in new tubes and ChatGPT says that just the phono stage needs to be on but, not the preamp. 

The amplifier has a resistor to signal ground that sets the input impedance. Since the preamp is connected to the amp, they share a common signal ground and the signal passes through the amplifier. In other words, the preamp is loaded by the amplifier whether the amp is on or off. The preamp doesn't know the difference.

Thanks for the help!  Just out of curiosity, does a signal from a CD or other source need to be fed to the preamp, or does the preamp just need to be powered up?

Ideally you want to feed the preamplifier a signal. In theory, the more diverse in spectrum the better. Since you've been using you CD player an excellent signal generator is the XLO/Reference Recordings Test & Burn-In CD. Specifically track 9: System Burn-in. Best of luck. (In a pinch FM white noise is also reasonably effective.)