How much does volume matter when breaking in amps and cables?

Zero
What level on the sound system do you chose when you are "breaking in" your new car ?

tcatch, You may want to check your manual before running your amp without it being connected to speakers. Some amps will be damaged by that. 

Tcatch, that’s a good question. I guess one could purchase cheap xlr/rca adaptors for breaking in. 

As long as we’re on the subject.... If one is breaking in a power amp, is it necessary to connect it to speakers, or could you get by with just running a signal into it? And if the amp has both XLR and RCA inputs, would it be necessary (or even helpful) to use the same input during the break-in process that one intended to use after break-in? (I ask because it would be convenient to break in my new power amp in a secondary system that doesn’t have balanced connections, while I continue to use my old amp in my main system.)

He's asking about electronics and cables not speakers....

The XLO Test CD with burn in track suggests playing the system loud and continuously for a week or two. Use blankets or jeans over speakers to mute the sound. Otherwise, you know....🤪

+1 lak 

IMO: Other components don't need much volume at all, just turned on with a signal running through them.