Glossator
Head-Fier
Actually, I think you are both (potentially) right and also wrong!Yes you are wrong. My DC4 powering my Dave (and one powering my Mscaler) are both absolutely quiet with no noise from it whatsoever. I also have a DC3 and likewise there is no noise from that even if I rest my ear on the case.
My first DC3 (mid 2019) did buzz and Sean suggested various solutions - I cannot find the emails immediately but causes can depend on your circuit.
However, my DC3 'evolved' and Sean added some sound shielding and changed the transformer - there is now no trace of hum at all (which is also true of its younger sibling built to the same design).
So, my take away is (i) hum is certainly not inevitable, and (ii) the great thing about Sean's design is that he is really constructive and approachable - so if there is an issue he will help fix it.