Reliabilty, Keeping Equipment Powered on or off?

I generally keep my system components powered on because the system does not have to "warm-up" when I sit down for a listen. I do know that reliability is usually calculated by POH (power on hours) however this calculation IMHO is a broad brush stroke. I do power down certain components that are not required to be left on to sound their best, such as a Luxman T-117 tuner and Wadia 171i Dock . However, my Krell IA, with the volume turned all the way down runs pretty hot, so hot you can't leave your hand on it. When turning the volume up on the Krell to reproduce the live event sound level, you can fry an egg on it, so I can only guess the Krell was designed to handle this kind of heat? However, back to the other components, such as DAC, SACDP, Headphone Amp, etc. Is keeping everything turned on asking for trouble or is leaving it on best to prevent thermal expansion and contraction which may be detrimental?
Do /you/ notice a difference in sound quality if they are left on? I would leave them off. I assume the DAC and CD have standby modes.
This subject has been discussed previously in the forum, but does get resurrected every so often. Personally, my view is "it depends". Putting aside the added electrical cost, minimal or not, I completely power down all of my components when not in use. Meaning, I do not care for "standby" mode for hours on end until I'm ready to listen. The caveat here is that I power down in cases where I know the next listening (or watching as my video is connected to the same power source) opportunity will not be for another 24 hours or so. If, one the other hand, I listen/watch something in the early AM and take a lunch break with the intention of listening/viewing an hour or two later, I would leave the components on. 

While I have solid state equipment, other considerations may need to be accounted for in the case of tubes or other circumstances. I do not know, but I'm reasonably certain others will chime in.

I simply do not buy into the notion of "warming up" my equipment. That said, I do know that electronics of any kind should not be exposed to "extremes". For instance, if for whatever reason you have your amp in your car and it happens to be the dead of winter, you wouldn't want to take it out the car and immediately set it up at your listening location, turn it on, etc. So the caveat here is that equipment remains at normal room temperature. 
You can turn off the DAC, SACDP, Headphone Amp when not in use, as they will warm up quickly before a listening session. 
Buy a low dB computer type fan for the Kell and leave it powered up. It takes a few hours for an amp like that to warm up for optimum performance.
I don't know if it's true, but I've heard that one should keep their tuner on, even when not actively used while otherwise using their system.
Perhaps some one with more definitive knowledge can chime in?
As Gdhal indicated this question has been discussed in a number of past threads, with lots of opinions being expressed but without much in the way of consensus being reached.  IMO all that can be said with confidence is that it depends on the specific designs that are involved, and on the usage patterns of the particular user.  And on the particular user's feelings about energy conservation, especially with respect to components that consume a lot of power.

One thing you might consider doing, if no guidance on this issue is provided in the manuals for your specific components, is asking the manufacturers of the specific components for their thoughts on the matter, while describing your typical usage patterns to them.

-- Al
The manufacturer of my amplifier (Odyssey) recommends the amp stay on at all times unless you won't be using it for months on end.  My Stratos amp has been left on since April 2010 and only turned off for 10 days when we went on a long road trip.  My amp has always worked flawlessly and is never warm when idling or being run hard.
Hi, and thank you!

After digesting the posts above, I will be powering everything down with the exception of the Krell. The Krell sounds best when left on and I do not want to introduce thermal stress on the 24 output devices, i.e, cold to hot, hot to cold, etc. I think for this amp, leaving it on with the output devices "warm" is the best way to treat them?

Thanks to all,

From the standpoint of safety, longevity and energy savings, it makes sense to power down everything.  This is particularly true of tube gear.  I can understand not wanting to power down amps which can take a really long time to come back up to song, but, these are exposed to the most heat from being left on, and these can do damage to speakers if something happens while you are not there to power them down.  As for thermal cycling, that is really not an issue because it happens relatively slowly.  If you look at rating of most parts, they include rating by operating temperature--the higher the temperature the shorter the life.

I only keep on what is meant to be on all the time.  That means I don't power down my music server/NAS.  It would take about 20 minutes to bring the server network back up if I turned it off (components have to be brought up in a particular sequence).

One thing not mentioned. Power line transients. The longer something is kept on and connected to the AC power, the more potential for damaging power transients to destroy components in your power supplies. If you have good line voltage protection (like a Furman line voltage filter, for example), then this is less of an issue. But also be apprised that many line voltage protection devices (like MOVs) have a limited number of transients they can absorb before they fail and you have no further protection.

Power brown outs may create similar problems. If you have frequent or constant power line drops, this can also be hard on equipment as it shuts down due to the low voltage then re-powers as the voltage levels are restored. All this may be happening while you are gone and unaware if you leave equipment powered up continuously.
My Rowland Cadence / Coherence preamp/phono doesn't want to be powered down, in fact there is nothing in the manual about turning it off, ever. Worse, if you power it down, you have to go through a whole blah-blah to start it up again properly, vis-a-vis the batteries in the power supply, and to top it off it forgets where it was. I turn the preamp down to zero, and that supposedly shuts down almost all of the internal circuitry.
A suggestion that I have deemed to worthwhile considering is the contention that amps,,etc  are most at risk for damage when a unit is turned on.   Inrush current.    While undoubtedly there are  electrical components in place to help counter any effects of the surge --It seems to make  a lot of sense to subject units to turn on current as little as possible.     That being said-- I am not leaving my tube amps on nor my s.s. amps on especially my class A amp.  I do leave a Trends amp on as it is quite economical to run.   It is more of a summer amp.     I am leaving my 2 tuners on that are used daily---especially considering they are vintage tuners and dont want to subject them day to day to inrush current .  I listen to my systems on a daily basis.  My Sonic Frontiers Line 1 has a standby and I use that.  If I am going away for overnight or even the entire day I usually shut it off completely.   As long as I am in town  I would not want to be powering it up every day subjecting the tubes to start up current of which it is known to subject tubes to more stress .    Re/power line failures.   I think a good portion  of the high quality equipment made  and even not in the higher price range comes with protection circuits for power failures and surges.    They have to design this into the circuits --it is part and partial of designing a quality power supply.      I recently bought a pair of Emotiva mono's  and am surprised at the lengths this company has gone to in protecting the circuity for a not much money at all considering what I paid for my Pass amp on the used market.  .     I leave the Emotivas  in standby and have been using them primarily in my main system as of late.   This with a  $5k plus (new) Pass amp sitting idle.       

I can't speak to all equipment, but I am very familiar with Parasound as I have schematics for the JC1, JC2 and other products such as the 2200ii and P3. Although well designed (as good or better than most), there is no voltage transient protection besides filter capacitors. Transient voltage protection is typically not provided by most manufacturers and is left to sand alone outboard line filter and transient protection devices.
So many with different opinions.
IMHO, i would rather deal it a more scientific way. Generally, if the measured temperature on the chassis (using a temp probe) is less than 35 degree C, it is safe for equipment to remain on 24/7. If you need to be more specific, just open up the chassis and measure the heat of the components inside (i won't be responsible for any damages to your equipment and to your own safety), if the temp of the components is hovering around 40-45 degree C, it is still OK to be on for 24/7, BUT with one caveat , you gotta search for the lowest temp rating of internal capacitors. If it is rated at 70 degree C, then the internal ambient temp and\or components gotta to be less than half of that, i.e. 35 degree C or lesser. Capacitors life span and other electronic is affected by temp and their specification rating would drift faster over time due to heat.
I was told as rule of thumb the components that run hot - not just warm, should be left on at all times along with good line protection. I think this applies to most if not all power amps that operate in class A. Extreme temperature cycling puts a lot of stress on electronic components and can reduce their life expectancy even when they are designed to handle those conditions.
If they (audio equipments) are designed to handle those conditions, then of course , it should be left on without problems. It's those equipments that use poor quality parts that have "borderline" specifications on heat, current, mechanical tolerance (thermal expansion) etc..  that we should take note of irregardless they are running hot during idle or operating in Class A or not.
I've previously noted that leaving things on even at the suggestion of amp designers is the domain of wasteful boneheads who, as an example of wasteful boneheadedness (!), might also leave their cars running at all times to insure proper engine lubrication without that pesky "start up" stress, and leave refrigerator doors open to obviate door hinge wear, etc. I've since completely changed my stance on this issue (although I turn my rig off so I don't have to think about it blowing up when I'm not listening to it) as the rampant wasteful tendencies of people have irretrievably set our demise in motion, so you might as well waste whatever energy you can. After all, your audio playback standards can make you happier, and will help assuage any stress from, for example, an area of African farm land the size of Alaska recently being rendered unusable from rising sea water contamination. Who cares? Get yer Mahler on and you can let the kids worry about all the other stuff...  
There’s no one right answer anymore.

The biggest issue with on/off cycles was the initial current surge that goes through the transformer and power supply capacitors. They are much better now than 40 years ago, and many amp makers have added soft-start circuits which prevents this from occurring.

So the concern for turn-on surges is less than it was historically and leaving your devices on 24/7 has a down side. All power supply capacitors are rated for a certain number of operating hours so even while you are away you are running the clock down on them.

The higher temperature caps a vendor used, the longer they will last in general.

The other thing to consider is AC surges and spikes. Depending on where you live, like say Florida, these can really wear down the caps quickly. Of course, you also run the issue of a power surge happening when you are away.

So, I’d say keep your low power equipment turned off unless you have a good surge supressor. Then leave them on all the time. :)

As for big items like the Krell’s and tube power amps, I have a tough time stomaching the damage to the environment I’d be causing. If they are relatively recent models, I wouldn’t be surprised if they already had built in soft-start circuits as well as more modern caps that are less vulnerable.

Personally I’m off in class D land so for a total of 15 Watts at idle I leave my stereo amps all the time through a Furman surge protector. :) The amps are also excessively well cooled, so the wear and tear on them operating 24/7 is much less than your Krells I'm afraid.


That Krell worries me....why don't you just call Dan in Cave Creek, Arizona and ask him.   Its probably pure class A, but still.....heat is a destroyer.
All my gear is in stand by or full power 24/7 if it does not have a stand by unless i am away for the night then all gear is powered off. All gear is solid state. I have tried both ways and my sacd/cd player and pre amp all sound better when left on. Was told this by the factory rep better to leave on.

I used to leave my class a/b on 24/7 but my new class A gets turned off. I don't listen to music on week days so I normally turn it on Friday and off on Sunday. I guess I need to reach out to the manufacturer (Accuphase). I can't seem to find any info about it on the website.

Some of the replies have suggested there is no right answer to this question, I beg to differ. I am not by nature, a tree hugger, but we do have to consider finite limits on the worlds fossil fuels, if not, Global Warming.

I think we have to distinguish units with and without a standby facility, or those that automatically switch to standby when not in use. Units that stay powered on, particularly Power amps and even more so, Power Amps that run warm, usually Class A, are using an appreciable amount of juice. Just how much power does it need to heat up a heavy metal cabinet with components that don't include a heating element.

 Something I don't think that has been mentioned, is fire risk. The commonest cause of house fires in the UK, is electrical equipment left on standby, admittedly mainly TVs. I have never heard of a HiFi Rig causing a house fire, but it must have happened.

 All in all then, I think kit should be turned off when not in use for a number of hours. I do believe kit needs to warm up to reach optimal sound, but in my experience, this does not usually take more than half an hour.

My REL subs are always on, but the standby power is so low as to be insignificant. The rest of my gear warms up (tube amp) and sounds great. The "right answer" is to turn everything off since the benefits described by ANY manufacturer are minimal, but, as I noted earlier, people have lost the climate change battle as India and China ramp up thousands of coal plants, overpopulation driven by ignorance is likely to remain unchecked, and audiophiles deserve to have as much fun as possible. They just do.

The part that always seems to fail for me is the on/off switch.  My Classe amps suffered multiple switch failures.  The Cary integrated has needed a new switch as has my VAC preamp. 

Stuff breaking is just part of reality.

Uh…just had to leave town for 3 days due to unexpected family thing and uh…left everything on including my tube amp. Man...
Turned everything off last night after leaving everything on for an extended period of time (weeks). Well, when I powered on the Krell, there was a distinct "pop" sound, now the remote control does not work! Learned my lesson.