Leave it on?

If you listen every day or so, leave everything on.  If you listen once a week or less, turn everything off. I also turn off everything delicate when thunder boomers are approaching.  I lost an amp once from lightning.

Turn off or leave on 2.  The benefits of from the off starts.

Manufacturers and dealers will always say “keep it turned on” as gear sounds better warmed up. We all know it is mostly true. They want us all to be happy with our purchase’s every time and want revisits buying more stuff further up the price line. They will not want to be involved however if your place burns to the ground afterwards.

Said on here….

”Standby mode keeps the solid-state circuitry of the amplifier in a reduced power mode, maintaining excellent performance benefits while consuming little power”

Hmmm…. Another way of looking at this…

Leaving any car engine turned on keeps the engine warm in the reduced power idle mode, maintaining excellent “from the off” benefits while consuming little petrol.

Everything wears out from when you first start using it, and if you continually use it. Electrical components permanently turned on is not guaranteed to extend their life.

Another thought….. Have you ever added up the wattage of all the electrical devices in your home on permanent standby mode? There may be a big surprise as to how much power idles away with your energy bills. 

As you can see from all these replies very equipment specific. I don't believe Paul was issuing a blanket leave it on but rather if you have standy mode then use it as it keeps the electronics consuming little power but ready to perform quickly at peak efficiency. 

I keep SS gear on all the time unless on vacation or a storm.  
 

How long will you keep your new gear? 1 to 20 years as I am an audiophile 🤓.  Just don’t know. 
How do you feel about global warming? Really not a thing you know.  Current thinking is coming around to this thought. If you haven’t studied it, wait till you learn that we can’t even measure the Earth’s temperature accurately. Never have, never will. Our instruments, we humans, and our methods are flawed.  Always will be. 
How confident are you leaving other appliances on all day and night? Like my refrigerator? HVAC? Some lights? Water heater? I think you get the point. 
How would you feel if your house burnt down? Not good.  What does this have to do with the topic?  I think interjecting fear on this topic is not helpful. All of our homes have live 120 V outlets and electricity networked throughout the home. Fires do happen and that is certainly a possibility in most any home.   However, suggesting that leaving on a streamer, dac, power conditioner or amplifier  is more likely to cause a fire is really not serious.    
 

In most cases this is just picking nits. Well-designed gear that is relatively low in idle power draw (preamps, class D / G / H amps) should have NO problem either way. Do what you like. Gear that is high in constant power draw, are therefore heat dissipation - tube power amps, class A and high bias AB solid state power amps - should really be kept OFF when not in use. In my experience, hotter components are also more likely to sound good quickly after warmup - simply because they hit thermal equlibrium quicker. SS is always slower to warm up than tubes.