Value of burn/break in?

I have found 3 levels/processes of burn-in that operate in audio systems. Each is real (judging by subtle but perceptible sonic results) and has its own time requirements:

1 - New electronics:: Solid state electronics as well as individual tubes benefit greatly from burn-in when new. My nominal/minimum burn-in time for any new component is 100 hours. BTW, burn-in for certain purely SS pieces can be much longer. For example, my two Audio GD multi-bit DACs (NOS 19 & DAC-19) each required ~400 hours before the sound stopped changing and stabilized. Other owners of these DACs had warned me of this extensive burn-in requirement...they were right.

2 -  New speakers/headphones: These need ~100 hrs initial burn-in.

3 - Initial turn-on of system: As others have mentioned, SS units (ones that have already had initial burn-in) benefit from simple warm-up when first turned on (usually 15"-30" does the trick) and can be left on 24/7, particularly line-level components (vs amplifiers). I've also found that certain tubes require ~30" initial warm-up before sounding their best.

In the case of cables and wire, especially tonearm wire, interconnects but also any wire, complete burn in never occurs without resorting to some break in means other than simply playing music for several hours a day, or even ten hours a day. This can be easily demonstrated by using the AudioDharma burn in machine on cables that have already been broken in for, say, two years or whatever while in the system. Music is neither the optimum signal to achieve complete break in nor is it high enough in level. And it’s an old wives tale than fuses break in correctly no matter which way they were originally inserted. This can be shown to be false by reversing the fuses one at a time and observing by listening which ones were inserted in the correct direction and which ones weren’t.

Thank you. I have a Jolida Fusion Preamp with a level 1 upgrade as follows:

Replacement of 13 capacitors with Clarity Cap ESAs. Gold pin 12AX7 tubes.

Thank you. I have a Jolida Fusion Preamp with a level 1 upgrade as follows:

Replacement of 13 capacitors with Clarity Cap ESAs. Gold pin 12AX7 tubes.