How hot is too hot?

hahahahahahahhahahaaaa,
 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.