How hot is too hot?

When i leave my Parasound Hint 6 on overnight, it is hot to the touch (top grill), not warm, in the morning. There is nothing on the sides and 6 inch clearance on the top.I even tried switching the input to something nothing is connected to - like AUX or PHONO. Doesn't help. I have to turn it off now when i don't use it. No big deal, but it seems like something must be wrong to produce that much heat when not in use.

Is this normal? What part of the unit produces that much heat? What can i do?
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70 watts at an Idle, sure its going to be warm to the touch. That's 150.00 dollars a year to stay on. It's one of those you should turn off after using..

Think about leaving a 70 watt bulb on in a room it a bit of heat...

Will it shorten the life leaving it on all the time? Sure it will. Everything needs to be cycled OFF, if not just to cool a let the caps reform every now and then. Once a week is good if they run cool enough. If not shut down.

Normal, but as stated, there is no reason to leave that on all the time. Just leave it in stand by while not using. Try hot! My Pass amps run at 50-53° Celsius when fully warmed up. Nothing to worry about. 
Are we talking Neil Diamond Hot August Night hot, or Buster Poindexter Hot Hot Hot hot? Oh, Class A hot? Situation Normal.
I would have to say there's something wrong. I have a Hint 6 and it stays on 24/7 and I wouldn't say it's anything more than warm.
The Halo 6 has the main power switch on the rear panel, so the switch on the front panel is a standby. Do you turn the volume all the way down to zero after listening? If you don't, try that. If you do, turn the front panel switch off after listening and back on 1/2 hour before listening. Always leave the rear panel power switch on.
Obviously turn it off overnught if not playing..
Class A runs hotter on idle. Just warm it up BEFORE play, off after. 
Prepare to pay the power company.
You have to measure the temp of both heat sinks under the hood with an infrared thermometer. If one is much hotter than the other, then it's a problem. Heat sinks shouldn't vary by more than 5 to 10 Celsius. If both sinks are the same temperature and the amp isn't tripping off on thermal overload protection, then it's okay. Unless you fiddled with the bias adjustment pot, which I assume you didn't.
call parasound and ask them if this is normal and if they recommend you shut down or place into standby when not using

looking at hint6 specs it has a ’high bias’ class a/b amp section, so yes it is quite possible it would run fairly warm in normal operation, and it is likely why they give you a front panel standby option
70 watts is 70 watts. 
Specs says it idles at 70 watts. That is going to be warm to the touch for me an old mechanic and HOT to someone that has girly man hands. :-)

My FW J2 runs hot. That is even taking the nerve damage to my hands into consideration. It sounds great,and makes a nice space heater in the winter months. I wouldn’t have it any other way. I also don’t leave it on 24/7.  It takes about an hour or so to hit full stride. 
Call Parasound and ask them.  They might say it's normal or they might want to have a look at it.  It might be running hot because of a problem like hf oscillation or a ps problem.  
Depending on the safety standard used for compliance of this unit the maximum temperature of operating device on the surfaces that a user can touch is 70 C (158 F) for metal and 95 C (203 F) for non-metal surfaces.  That's pretty hot, so a prudent manufacturer would allow some headroom as not to burn paying customer :)   It is easy to check with any infrared thermometer.  If the enclosure is not black, put on it a piece of thin black electric tape, let it sit for ~15 min. and test - non-black surfaces have emissivity coefficient which you may not know right off hand.  If the temperature exceeds the above numbers to me this would indicate either a) non-compliant design, or likely b) something went wrong and needs to be addressed, preferably right away.
I have an esoteric f03 and idle is 300 watts.  It is uncomfortable to the touch for more than a few seconds.  Have to turn it off when not listening here in Tampa   The best of tube and solid state sq.  75 watts is a lightbulb left on
My system is powered on night before (24 hrs) usually. We don’t have class A , we have A/B. Runs a lot cooler!

   Class A I (as mentioned) I would have powered OFF, when not listening.
 Class A, we would power on 6 hrs before a good listen, and play source for an hour so at low level music, then after an hour, play a wee louder,  class A is a different beast!  Warms up quicker, and don’t dissipate heat as fast as a A/B amp. 
 Will sound a wee better than most when warmed up. 
 We warm up the odyssey kismet for about 4-5 days after turned off for extended periods. 
 But, the class A (when mentioned class A for first 1-15 W) is NOT real class A) we don’t think!,
real class A amps which are all class A full time ARE REAL CLASS A AMPS!!   

 As mentioned, call Parasound and ask for a tech!

  Idle mode is good. Turn off when not in use. 
  Ours are always off and unplugged from wall or Furman when down time is going. 
  Will leave on for days at idle when going to listen for a weekend. Powered on on a Wednesday, Thursday evening, left on until Friday until warmed up. Always sound so much better. Like a laser beam to my ears when warmed up.  We also leave the pre-amp and source on at same time amps are powered on, to get everything warm, it does sound so much better, SOOO MUCH BETTER!!’ 
Cold listening (while still good) has a .....not sure,.... not as soothing, relaxed tone to music listening. Warmed up electronics just have an enveloping, inviting, NON fatiguing, more inviting sound/tone. 
Even the wife noticed, playing a few UFO, Humble Pie, Y&T, even played her fav, Hysteria by that once great NWOBHM band Def Leppard, started on Friday afternoon, and played much of the same throughout the weekend, she did notice a more soothing, and detailed sound, and she cares less if it’s on her iPod ear buds , or a Bose wave radio, to her it’s all the same,....BUT, she did comment at the sound one Friday late evening, that it sounds different, it sounded better to her, like it was being played at a stadium,.......
she did noticeably hear a difference.  That amazed me. 

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That auto “on” is cool stuff!

 Mine don’t have it. 
My old system did I think, Onkyo m-504, tx-890 as pre amp, few CD players, Onkyo dx-7500, had an IR cable, but never used it. 
 you could just about fry an egg on top of my Sugden amp when it's left on all weekend,you shouldn't have anything to worry about..
I don’t know audio products run hot it just take watts to make sound, I have some power amplifiers from crown and going near them you feel a change in temperature a little more when they are being used as opposed to idle. Also remember as things age they tend to degrade so replacing anything that is used to transfer heat or if it can be upgraded should be looked into if it bothers you that much about the heat 
Thanks everyone for your replies. When i bought the unit i called Parasound  just to ask if i can leave it on. They said i can leave the amp on 24/7 as it was designed to do that. I didnt ask about heat back then because i didnt notice it at that time.  I sent an email to the Tech dept the other day. Have not heard back yet. 

Some of you say - leave it on, others say turn it off until needed. I can do that - not really a big deal but i still wonder if the amp is faulty somewhere. 

Some of you mentioned an infrared thermometer. Any suggestions for an inexpensive model? I'll probably never use it again for anything else. I should ask my local facebook group to just borrow one.

Your amp is class A/AB: it can getting warm. A Perreaux  gives ( on the display) 65°C and may not be hotter than 90.  After listening switched it in “off”. The warming up will be 30-45 minutes.
I run Class A.  I wouldn't leave it on when not listening.  The heat will shorten the life of components, particularly capacitors that will dry out.
I wouldn't bother with a thermometer, if it's too hot to hold your finger on it, that's too hot.
Once again. I have the Hint 6. It stays on 24/7. It comes nowhere near to being hot even when I'm driving my Dali Opticon 8s at higher spl. I venture you have something wrong.
Heat is normal 6" clearance is very bad should have at least 1foot.Put it on a stand which will be much better for heat dispersion.It should be shut off when not in use 1/2 hour before listing turn it on.Good luck.
epz, the Hint 6 is an excellent unit. It has a thermal breaker. If it gets too hot it will shut down. If it is not shutting down you are OK.

clearthinker, I think in general you are right. My old Krell KMA 100s were class A and burned out after 20 some odd years. Components are much better now and more heat tolerant. I expect their life span to be longer. 
It seems all the amps I am interested in run hot. In an attempt to improve their life span I use a fan system which you can see on my system page.
My approach to the fan noise was to put the amps in the room under the speakers on a shelf against the ceiling. I did have to put a potentiometer on the fans to slow them down. At full speed I could hear them upstairs.
@epz- As others have mentioned, leave the main power switch on 24/7. That is what Parasound is referring to. Just put it in standby when not in use. That’s pretty standard practice for amps. 
Who was the person that started the story, you should alway leave you audio equipment amp on...Who started this was it Thomas Edison? So he could make more money....or the audio equipment company who says alway leave your audio equipment on....just leave the volume down to zero....WHO....does anybody out there have the person's Name?   The only thing I leave on that's electric in my home is the refrigerator and my electric clock....everything else is shut OFF....yes my microwave to.The clock on my stove is always cable box is off...and I save alot of money on my electric
Aside from dadork worrying me - because he has the exact same unit and his never gets hot; I am turning off the until from the front "standby" switch every night, and put it on when i use it. I always left the rear panel on/off on. I will try to lower the volume to -0- to see if that helps as was suggested.
Several decades audio repair, and can tell almost instantly whether unit on 24/7 or shut off when not in use.
The heat cooks the components (which are designed for heat to a point) AND the solder, which in units made after 2006 will be Lead-free solder and does poorly in high heat cycle environments.
My experience the solder joints will fail before most components.

Turn it off when not listening, solid state warms up very quickly. I get home and fire up the stereo and it's ready for listening within 15 minutes.
My 3 cents (inflation)
Turn it off when not listening, solid state warms up very quickly. I get home and fire up the stereo and it's ready for listening within 15 minutes.

wise advice imo

or use the standby mode if the unit has one
What you have to consider is the Hint has a HT Bypass which would mean though control functions are relinquished the Hint is still operational if you are running your mains throught the Hint when in HT. Most people leave their TV on all day if not listening to 2 channel, therefore it would be on all day as well. I'm not sure why yours would be hot. Honestly mine never gets more than a bit warm.