Feedback in AV system

Pretty experienced Audiophile with a feedback issue that has me stumped. Digital sources (cable/ DVD) work fine without hum, but when I switch to analog sources (turntable, CD, I have noticable hum. Have unplugged individual components to isolate but to no avail.

Suggestions on best places to investigate?
Need conponant list. Do you use seperate preamps with pass through?
I had this problem after redoing my cables. Had redo again because I had power wire too close to each other. I seperated them and it went away. After I went to find it and traced it back to the 2 differant conditioners I use 1 for analog and 1 for HT and if the power cable were too close it caused the noise but only in analog. Both conditioners come from the same power source.
Unplug the cable TV or satellite antenna cables. Grounding of these systems is the most common cause of ground loops.