Static noise when power up PreAmp and Amp


I just learned that my system has a static noise when power up the PreAmp (Mcintosh MX136) and Power Amp (Mcintosh 303). It seems to be happened to the front channel "Left & Right" when input selected to CD mode. Does anyone have similar issue like mine? Please advice how to fix it.

Tried to look anywhere under the cover of amp/preamp see if there any cold solder joint around IC recepticles...?
Thanks for the advice! It just happened recently. The preAmp and amp haven't been moved since both sat on the rack. I will check the XLR cables. Thanks again!