There is no easy answer. The life of electronics comes mostly from the life of aluminium electrolytic capacitors. It is mosty dependant on ripple and temperature and the quality of capacitor.
First, it should be japanese brands like rubicon etc.
Temperatures inside are around 42 deg C, so the life should be for best caps around 15 years. This is long but not very long. My tube amplifiers have 12 years now but I do a maintenance by myself (as I have built them)and check impedance of caps and ESR every few years. In DCS you have at least 100 capacitors so no way to replace them. I would switch dCS off completely if not listening for more than 10 hours. I have also a fisher tube amp from 60ties and some electrolytics are like new,but you don’t keep it on 24/7