Elinor: I work on electronics for a living. The gear that gets cycled off and on the most and / or isn't used for extended periods of time is the gear that comes in for the most repairs. Both of those problems are related to in-rush current, higher than average current consumption and massive thermal swing. This is what damages componentry the most. That is, unless the product runs phenomenally hot and isn't built to dissipate that much consistent heat. It is easiest to avoid these problems by not powering the device down. The device maintains a more consistent operating temperature, there's no in-rush current involved and current is only drawn as needed.
Gear that doesn't take very long to thermally stabilize and makes use of "soft-start" circuitry is fine to cycle up and down. Obviously, tubes and lasers have finite lifespans, so one should take care of how they use these. This is not to say that turning off a laser based audio device is beneficial ( it typically isn't in terms of sonics and thermal stability ), but that the lifespan of the laser may be reduced if it isn't. Replacing a laser on most of these devices is not hard though and should be done after a period of time anyhow, as output levels and calibration fall off due to use one way or the other. Sean
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