SRM-727II problem

[brat]

I've posted my complaints in the other head-forum but no adequate responses or even any guidelines have been written.

For the last month I hear a conciderable increase of the highs of my O2mk2. Somehow the highs "opened" and become more shrill and noticeable, some squeaky and ticking sounds protrude above the whole sound "picture". I mean sounds like the sound of a harpsichord or the movement of the fingers over the quitar's neck, or some "parasite" sounds which are found in all acoustic records. It sounds to me like sharp peaks in the upper frequencies range. Before this transformation the sound of the O2mk2 was smooth and laid back without anytning annoying and distracting my listening. Now it's more k701-like In fact now the amount of the highs of my Omega are much louder of the k701's.

After comparison with another SRM-727II it was found that my SRM-727II causes the sharp peaks of the highs and the overall harshness and sibilance.

The sound symmetry of the problem makes me think that it is in that part of the circuitry which is before the channel separation.

Any ideas what may cause these shrillness and harshness of my amp?

Has anyone bump into such a problem with any electrostatic amp?