Music Hall Turntable Hum?

I have a slight hum when I use my phono that increases with volume to the point that when played at loud levels it actually starts feedback with my speaker. I mean bad. System is dead quiet with CD(Music Hall also)I have played ground loop search but think it may actually be something else. Speakers are Def. Tech BP2000 with built in subs and the size of the room and wife dictate the distance I can keep them apart. Are there shielded IC's I could use to prevent the feedback? The MMF5.5 has wall wart plug. Is this EMI? Any help or thoughts would be appreciated. Thanks