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.
This problem has done to death (i.e., search the A-gon archives) but...
1. Are you using a dimmer switch on any lamps?
2. Does hum come from both tweeters or only one?
3. If only one hummer, switch the speaker cable and see if hum follows. If yes, then work your way back to preamp and swith cables there and see what happens (we're trying to find the source of the hum).
4. If you have cable T.V. hooked up to your system, disconnect and see if this helps. These are bad,bad,bad...
5. If possible, open your speaker and check all connections (disconnected from your amp, of course).
6. Try to borrow some ferrite rings from your "friendly dealer" and see if RF (radio frequencies) are causing the problem (you run your interconnects and speaker wire through these and they "soak up" RF).
Hope this helps...
Ground lift the system.

(Dont use the ground leg on the power wire.)