White noise when XLR connection is used ...

Hello everybody,
I have strange problem when my monoblocks (Clayton M100) are connected to my CDP Audio Aero Capitole mkII with XLR interconnect, there is pretty audible white noise. When I disconnect XLR connection noise disappears. When Claytons are connected to CDP with RCA interconnect there is no noise, dead quiet.
Any idea why ? Any suggestion. Is not supposed XLR to be quieter connection ? I have tried many different RCA, XLR cables, always the some, so problem is not in a particular cables make, but in the connection itself.

Thank you for reading.
Just a guess, but I believe that the outputs of the Capitole are driven by 6021W tubes, and I would suspect that the tube or tubes that drive one or both of the two signals on the xlr connector is noisy and should be replaced.

Concerning replacing the tubes, this thread may be of interest.

-- Al
Thank you for answer,
if tubes are causing the problem why there is no noise when RCA is used, and why noise level is the some in both channels, both tubes degraded at the some degree ?
Sorlowski, without having either a schematic or some familiarity with the internal design of the Capitole, all I can do is speculate that there is a problem in some circuit element, perhaps a tube, that is common to both xlr outputs but not to the rca outputs.

Sorry I can't be more helpful. But see my response in the other thread in which you have posted about this problem.

Best regards,
-- Al