This is an interesting question, because the Miyajima Zero is one of the best mono cartridges out there, and, so far as I know, it was designed from the ground up to be a mono cartridge. Thus, unlike many "mono" cartridges on the market, which are actually stereo cartridges where the two channels were internally strapped, the Zero is not capable of producing signal (i.e., noise) in response to vertical movement of the stylus tip. It is of interest that Folkfreak cured the hum problem by using the "mono" mode switch on his preamplifier. Has anyone else had this problem, and was it thus cured? What is it about the various phono stages used by those who have commented that produces hum in some cases and no hum in other cases, presumably without engaging mono mode? Thanks to anyone who can help fill in these knowledge gaps.