How hot is too hot?

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.