Did you have any luck with this problem? I too have the same problem with my M-100s. Just spent the entire day buying and returning cables that don't work. But I don't believe it has anything to do with the mic setup in the cable , as I also have the basic cable that is supplied with the M-100s, it has no mic at all. I tried both cables and both had the same problem when attached to an extension.
I was able to make it "work", by loosely poking the extension into the V-Moda cable but as soon as I plugged it all the way in, it became very quiet. I believe only one speaker was working. So back down to the store I went and the young lady behind the counter (very helpful and knowledgeable) explained to me that I may be better off making a cable, but before I could do this I needed to find info on how the cable jacks are wired.
I can find no info on this at all. I really need to get my M-100s up and running via the Denon reciever so I'm not waking the family up in the middle of the night whilst watching movies (I'm an insomniac).
I'm only assuming that the M-80s use the same cable setup as my M-100s. Any help would be greatly appreciated.