PowerStrip (note the brand in the lower-left corner) is very useful software for adjusting low-level settings.
I don't understand why it's so hard to get the FEMALE version of the MDR plug - it's madness. For some reason, it seems nobody makes extensions of these cables.
Well, at the very least, an alternative to the link above to source the plug parts is here: http://www.mouser.com, part #'s 517-10120-3000PE for the plug and 517-10320-52A0-008 for the plastic shell; and then there's about 10 million variations for boardmount, angle mount, etc. But all male; if you want a female one, it seems you MUST get a boardmount, can't get a solderable one. I'm trying to make an extension for the cable, so I ended up buying a panel mount female, and will see if I can somehow manage to solder the wires onto it.
Update: ribbon cable DOES NOT WORK. I dunno if it's because 28AWG is too thin for the wires, or there's crosstalk, or what. But I used the connectors in my post above to build a custom ribbon cable (about 10ft long, wired straight through, pin1->pin1, pin20->pin20, which is how the original cable checks out with an ohm-meter), and I get nothing. Monitor powers up, flashes "no signal", then the speaker starts buzzing. Grr.