There are transformer types less perceptive to DC on the mains supply line. But sure, that‘s something to be solved elsewhere.
As said above, sometime other consumers down your street generate a little bit of an DC offset on the mains, which makes even very good transformers buzz. I had a JBL pro amp one with that problem.
I was referring to valves back in their day. Today the input C is nothing to be minimized per se, but optimized for RFI rejection. I wonder if vinyl playback-at-home optimizers understand the back and forth of decision making in detail fully. For best reason there is still myth and belief. We need that to make us trust the message transmitted via the record.
Anyway, seems I‘m out. I‘ll sell my trusty MC, replace by new basic MM, amplify via USB interface‘s microphone input, and equalize on the digital side, SINAD expected well above of what vinyl‘s mechanics is capable of. There‘s a handfull of records I’m not willing to miss in my life—as what they are, disks.