Heating up and cooling and amp

I recently had my Nakamichi cassette deck gone through and one of the things they did was repair cracked solder. They say this is common because of them heating up and cooling down. I realize that most higher end amps, as well as other equipment, have standby mode. I sometimes am listening to the stereo, then turn on the TV for a bit, fully expecting to return to the stereo later. Any thoughts on whether it would be better or not to just leave the amp on?
Sorry for the goofed up heading, I was trying to do to many thigns at once.
There are other post on this subject so do a word search. My Conrad Johnson FET preamp is on all the time. It does not have an on/off switch. CJ meant for it to be left on. Other than that I usually turn everything on when I get home from work and leave it on til I go to bed regardless of when or how much I listen. So it is warm when ready. On weekends this may mean leaving in on all day. My REL subwoofer can be left on according to the manual, but I also shut it off at night. I have a secondary system in my home office/den that I only turn on when in use, since not every day.
I am more curious about peoples opinions on the solders weakening from heating and cooling. My Levinson is in standby mode when not "on", so it is always ready. It does get warmer, obviously, when in use though, versus standby. I must say I am not deeply concerned about this as equipment generally lasts for years and years, just curious. If I can save on "wear" at all by leaving it on versus standby if I think I may use it again later I will.
As I said search the other threads. This was discussed in detail as recent as last week and there were links mentioned to online articles at places like Stereophile, Sound Stage and other magazines. The solder as well as wear on the caps and other electronics was discussed. Equipment with Stand By was also mentioned.
Look for "OK to leave the amp on" under Sound Advise. Original post was December 7th.
The biggest cause of equipment failure is either due to thermal related stress or surges due to in-rush current when constantly turning equipment off and on. Both have their ups and downs. As long as the equipment is adequately designed AND used with more than adequate ventilation, i prefer to leave it turned on. Not only does it sound better, my experience is that it will give you less problems in the long run. As Sugarbrie did state, this has been covered in depth both here and at the Asylum. Sean >