Hi Beppe,
Buy yourself a CD test disc.
By the way that impedance meter gave rubbish results. Either it was faulty or you used it incorrectly.
Dear Mr. Andrew,
after many ramblings I have found what can be the parameter to judge the quality of a transformer to be used in a power amp.
It is the REGULATION.
My case could well be the case of a transformer with a bad regulation.
I am ready to try a 625VA from Nuvotem-Talema with a 5% regulation figure.
In this way I will be sure that the problem is not in the transformer.
Then the filter caps and the diodes bridge, before throwing everyting away eh, eh, eh.
I take the opportunity to thank you all for your always great, kind and above all valuable help.
Yours sincerely,
beppe61