The noise is coming from the speakers. The noise was not there when I have the old set up. The noise comes on once I connect the tube amp to the preamp and turn on the amp power.
What causes loud num noise?
I have an tube amp using SE connections and have followed manual for the exact way to set up the system. How come the amp produce a loud hum noise, just like standing at the back of a big television. The noise is independent to the volume control. I plug the amp directly to a wall power receptacle. I have used the same receptacle connecting to my old solid state amp and it works fine.