A hum could be caused by many different issues. For starters, is the hum the same if you change the source? I had a hum when I selected my turntable but not when I selected my DAC. It turned out that my phonostage was too close to my power amp, and moving it killed the hum.
Try selecting one source component without playing music, and the volume high enough to clearly hear the hum, then switch the source and see if the hum changes in intensity or ceases entirely. This could lead you to determine if the hum is coming from a particular component.
if that doesn't do anything, read up on ground loop hum and how to eliminate it. PS Audio has a nice article on it. Here is the link: http://www.psaudio.com/ps_how/how-to-find-and-fix-hum/
A photo of your system may be useful, and/or a detailed description. Good luck!
Try selecting one source component without playing music, and the volume high enough to clearly hear the hum, then switch the source and see if the hum changes in intensity or ceases entirely. This could lead you to determine if the hum is coming from a particular component.
if that doesn't do anything, read up on ground loop hum and how to eliminate it. PS Audio has a nice article on it. Here is the link: http://www.psaudio.com/ps_how/how-to-find-and-fix-hum/
A photo of your system may be useful, and/or a detailed description. Good luck!