Have you isolated what component is giving you the ground hum? You should unplug them one at a time and see if the ground hum goes away! BTW, I ran into Raphael yesterday and he said he got your message!!
https://www.bing.com/videos/search?q=being+there+give+raphel+the+message&qpvt=being+there+give+raphel+the+message&view=detail&mid=49DFC796531BC867B4A049DFC796531BC867B4A0&&FORM=VRDGAR&ru=%2Fvideos%2Fsearch%3Fq%3Dbeing%2Bthere%2Bgive%2Braphel%2Bthe%2Bmessage%26qpvt%3Dbeing%2Bthere%2Bgive%2Braphel%2Bthe%2Bmessage%26FORM%3DVDRE
https://www.bing.com/videos/search?q=being+there+give+raphel+the+message&qpvt=being+there+give+raphel+the+message&view=detail&mid=49DFC796531BC867B4A049DFC796531BC867B4A0&&FORM=VRDGAR&ru=%2Fvideos%2Fsearch%3Fq%3Dbeing%2Bthere%2Bgive%2Braphel%2Bthe%2Bmessage%26qpvt%3Dbeing%2Bthere%2Bgive%2Braphel%2Bthe%2Bmessage%26FORM%3DVDRE