I thought it was kind of weird that the noise was constant in all channels. Definitely took away the magic of the pre-amplier. Finally opened up the Anthem, all 18 screws! Replaced the tube with it's predecessor, a Tesla -- possibly a step back sonically from what I had had before. Happy now ;-) Although, the magic sort of disappears as the last screws are torqued on. I really suspect metal covers are detrimental to the sound of components.
Anyway, I never thought that one tube would distribute it's noise to all channels and tubes. I suspect it was the filament, whose circuit is basically common to all tubes. I wonder what the noise mechanism is??
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