Well at least one of these cables is the genuine article, because they do sound better than M1500. I did some comparisons with the first 15 minutes of Top Gun via my hot rodded Pioneer BDP-51FD (direct RCA connection from Wolfson DAC to my Bendix 6900 line stage with Placette passive.) Its hard to describe, but the Sigma made the M1500 sound trashier and washed out in the bass which is not easily done since bass performance was a strength of the M1500 and it is a darker sounding cable. the M2000 Sigma also just sounded more interesting in the treble. With all this of course soundstaging was more impressive. Notice I've not commented on the midrange, and that was because the differences were very much imaging related, etc. My system does very low bass (Vandersteen 4a (like a 5)) and these differences might be smaller on a less full range system. These cables probably belong in a Monster Museum so I am starting one and will gladly except donations! (Just think you can write them off your taxes at original retail price.)
My best guess for my cables is that the lower capacacitance left channel interconnect has the newer PEX dielectric and that both are Sigma. I've seen ads showing a black body to the rca connectors versus the pewter look which I believe is newer. Black body ones would be older and more capacitive. I am not sure which is better. I would presume the PEX version, but I've seen an Amazon review comparing one of the grey m1000 versus the m1000i and the reviewer did not like the m1000i PEX.
I will be trying to jostle and peer through the black mesh around these cables under strong light. The PEX dielectric monster has always been a dark gray and the non-PEX light gray. I've inquired with Monster Cable's customer support (Speaker division) about capacitance specifications as these would be a great way to identify these cables.
.... I just spent like what seems to be half an hour peering through the mesh at the lettering on both interconnects (double magnification LED visor). By moving the mesh around I was able to make out the following, M2000 ultra coherent balanced impedance component audio interconnect cable. The lettering was the same and the cable color was the same. I expected to see some difference here that would account for the capacitance. The cabling appears to be the same. Through the mesh it definantly also looks dark grey like the PEX cables. It does not mention this, but the color is a strong indicator.
I am beginning to wonder if these cables had a 120pf capacitor (standard size) in parallel at one of the connectors. These cables had some frayed braiding and had heat shrink repaired by a dealer and perhaps they disconnected a capacitor. I've not heard of capacitors in Sigma.
The real fault for this situation lies with Monster (and other cable manufacturers too, Shunyata Sidewinder for example). They made cables that were physically indistinguishable from each other and yet they are different versions. Caveat Emptor. The M1500 faces the same issue. From images online the M1500 seems to sport the same RCA connectors as early M2000 (black body), but some have a grey mesh jacket while a few seem to have a darker grey mesh.
The M2000 connectors may come in five kinds. I see a late silver Pewter with a shading band around around the grippers. Then we have two that have more of a chrome finish, I am guessing the newer kind also have the shading band. Then we have mine which have no shading band that I can see. These also have a narrow black groove nearest the gold of the rca plug (the second closest groove is blue or red for channel). On all other versions this groove is the same color as the cnannel. I believe the black groove is older based on the fact the apparently newer cable in my pair does not have the black band on one end (two blue bands).
