Why Preamps Thump on Turn on

I leave my preamp on 24/7 - same as my amp. Both transistor. No thump from either on turn on/off. 

I turn on my McIntosh preamp and it then turns on my Mac power amp and Mac tuner,  No thumps or pops in my system.

Um.....

This happens with asr amir too - in his rush to have a reply for everything in making response to anything, he too never reads first much, in then making an answer to an entirely different issue of his own manufacture. 😆