If the noise did not follow the tubes, then it is not the tubes. Sorry to state the obvious.
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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