Leben cs300xs electrical noise in tweeters?


Hi!, I have a Leben cs300xs amp and I like the sound, but I discovered that the amplifier produces a little "electrical" noise in the tweeters of the speakers ( philips miniwatt with 91dB) if my ears are in tweeter... This is normal?.... Another owners of the Leben with the same experience?.... Thank you! 
thebalance
Hi, yes, I talk with the dealer and says that is a normal little noise of the tube amps. Is not a problem of tubes, the noise is also with another tubes, and the noise is the same in the two speakers. When the music play I do not hear the noise, but it bothers me to know that the noise is there! 
Try a "cheater" plug to temporarily lift the ground. If that clears it, you have a ground loop issue. If it doesn't clear it, remove all input cables. Is the noise still there? If so, you have an amplifier issue.
Try a variac, lower power=lower hum. Its very efficient with the leben CS 300 and the right chanel noise.