Humming noise from Tweeter?

It's normal to have a audible humming from the tweeter when you ear is less than 6 inches away from it? My system consist of a Panasonic DVD-Audio Player, Pass Labs X-1 Pre, Jeff Rowland Model 10, Revel Salon Speakers. The hum doesn't increase with volume, but when I mute the PreAmp the humming is reduced but still audible. All the gears are plug into a IBM surge protector strip. Could that be the cause the problem? Any leads appreciated.