A DC blocker is unlikely to eradicate the problem. I use one and they still buzz, although it does reduce it *very little*
I have transformers which have Mechanical buzz, which is what you have.
The ONLY way to entirely rectify it, is to replace the TFs with audiophile quality ones. Airlink and Toriody (I like Toriody) have audiophile quality TFs but drop them an email and specify that's what they are for.
I've used multiple cheaper Chinese alternatives and ended up throwing them out due to the noise they make
They buzz because the laminations arent glued together 100%. Whilst this has no bearing on functionality, it does make them noisy.
This one is in my valve phonostage, after chucking the noisy Chinese bought one. Worth every penny.
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