Need new tubes or other problem?

My ASL integrated amp suddenly developed a hissing/scraching sound on one speaker even without input. The noise is just there independent of volume knob position. I swap the tubes from one channel to another and the same noise is there on the same speaker. What is going on there? This is my first tube amp so I am just not sure.. Thanks for any advise!
If the noise did not follow the tubes, then it is not the tubes. Sorry to state the obvious.
I can relate to that problem in a way.I had similar scratching sound coming out of both speakers.The problem was coming from my Audio Research tubed DAC.First I thought it was the tubes(four 6922)and I did change them with another set.Problem was still there.Finally I had to send the unit back to ARC for repair.They did work on the power supply and installed fresh tubes.So IMO your integrated needs repair and you should contact the dealer e.t.c.
Best of luck