New Caps

A tech just replaced some caps (22ufd450 & 100ufd450) in my tube amp. How long might they take to burn-in? Does a signal need to be running through for proper burn-in. Since the music sounds pretty flat, I'm using my SS amp in the meantime. Thanks.
With those values, I'm guessing it's the power supply caps. In switching them, I don't recall a change in sound from new ones, especially the same value. Larger values tighten the bass, and change the midrange characteristics sometimes.

As long as the amp is on, and voltage is going through the caps, that's all it needs. If it was the coupling caps, then there might be a quicker break in with music going through them. As many as I have done, I don't recall any time period.
Someone else may answer that.
If they are electrolytics, then cycling them on and off in normal usage will be the best way to optimally form them.