Well, I don't know how they work versus other highly regarded plugs like WBT locking RCAs, but I use a pair of M-80 ICs from Bolder Cable and they sound fantastic--the cables, that is. I don't know what the cables would sound like with other plugs. If you want to see a plug shootout featuring the Eichmann, check out this link:
I tried a pair of Bolder IC's with Eichmann plugs (M-80's too), and promptly sold of my pair of Harmonic Tech Truth-Links, as well as a single HT Truth-Link. The HT Links use a very high quality locking barrel RCA design, btw.
If it was Bolder's M-80 IC's at work, or the Eichmann RCA plugs I cannot honestly say. I suspect it was a great cable design coupled with an outstanding RCA. I liked them so much I bought two more pairs.
The HT Truth-Links are much more expensive IC's BTW, but the M-80/Eichmann combo beat it hands down in my system, and IMHO. They are lightweight, grip very tight and just give you the impression that they "get out of the way" and let the cable carry the signal 'un-smeared'. As they say, they are not audio jewelry. I also use the Eichmann plugs for my digital coax (also Bolder's design).
Definately worth an audition if you are looking to purchase an RCA based cable.
PS--- I have a single, new (mint/unused) 1.5M M-80 IC with Eichmann left over and would certainly sell it below my cost if anybody is interested. $70. shipped. Drop me an e-mail.