Right--you need to burn in both the digital processors and the analog output end. Be sure volume is up to 100% if you have adj output, and have that connected to your preamp. I am of the camp where I leave all my equipment on 24/7. I think it's especially crucial for DACs as the crystal oscillator for the clock is most stable after being continuously powered on for at least a week. As Jedi says, you don't necessarily need to have your amps on, but hey, why not listen to music while you are burning it in? Then you can see how it changes over time, etc. And enjoy the music which is why we all are in this hobby I hope!
Burning Burn in question
I need to burn in a DAC/preamp that apparently needs a few 100hrs to come to live. My question is do I need to connect it to a poweramp and actualy play music during burn in? I would think that if there is no downstream load there will be voltage on the outputs but no current drawn. So you do in fact need to play music. Am I wrong?