I have some stuff that is left on all the time, and some that gets turned off and on routinely. And I have had some stuff fail and some stuff last the ages. There doesn't seem to be any correlation between those two conditions.
Yeah i know it wouldnt affect sound quality just a thought it might be better for the amps longevity if left on. I see that is not the case.
@rdenney is 100% correct.
If the electronic is designed to be on all the time, it will last as long as it's designed life. For example, server computers and even desktop computers.
I have a desktop computer that I use as a file server and media server, it's an used and refurbished product from Amazon, it has been on 24x7 for over 3 years now. The only issue I got is louder fan noise as the ball bearing on the fans of the computer is getting worn out, it is more likely that the fans on the computer will fail before the electronic.
For home electronics, they are not designed to be on 24x7, although the standby mode is; while some home electronics are left on 24x7 and still would not have any issues, just keep in mind, it wasn't designed for that. Also, keep in mind heat is generally a bad thing for electronics, and by leaving the electronic on 24x7, it'll be generating heat ,albeit at a low level that is negligible when there is no load.
There are no scientific nor engineering reasons that I know of that keeping electronics on will prolong it's life with the few exception of perhaps power related issues, such as inrush current as stated by others. But that simply means that the electronic is poorly designed or it's coming to the end of its useful life and therefore I said, it deservers to be fried at that point.
The other thing to keep in mind is electricity waste. For example, I am now contemplating if I should even keep my file/media server on 24x7 after doing the math: average load of say 80/wh; x 24h x365days x $.12/kwh = $84/year, at least I am using it most of the day. But for audio electronics, it is not being used most of the time if you keep it on 24x7, therefore, completely wasteful for no good reason.
Software-based stuff seems to me more likely to get zapped by incoming power issues, even though I have had generations of whole-house surge suppressors and no few surge-protecting power strips. I just had to replace a washing machine because the software-controlled parts got zapped, and this time--finally--I was unable to source a replacement for a reasonable sum of money. I had replaced the control boards in the washer and dryer several times. The dryer, in particular, is on a 30-amp circuit, so that whole-house protector is the only option there.
Perhaps do some investigation on this, how do you know for sure it's power surges? Sometimes, dirty power (i.e DC offset, extreme levels of AC line noise, poorly regulated power that aren't necessarily considered surges) can damage electronics. There's got to be some sort of device you can plug into your wall to log the quality of power, if that is the case, then I would contact your utility provider.
EDIT: After I made this post, I remember hearing of peoples' electronics would get fried at their house and the cause was power transients within their own home.
A quick google search yield this: "Electrical transients are momentary bursts of energy induced upon power, data, or communication lines. They are characterized by extremely high voltages that drive tremendous amounts of current into an electrical circuit for a few millionths, up to a few thousandths, of a second."
"A range of equipment creates internal transients: from copiers to coffee makers, vacuum cleaners to variable speed drives, and from fluorescent light ballasts to furnace igniters. Studies have verified that approximately 80% of transient activity at a given facility is internally generated. Copiers and laser printers are notorious transient generators as are heating and air conditioning systems. Any time an inductive load is either powered on or off it generates a low magnitude surge impulse that propagates back through the electrical system."
Source:
https://alltecglobal.com/es/what-is-an-electrical-transient/