I have been running the Black Mambas for over six weeks. They have improved immensley over that time. Initially they seemed to lack detail if not a tad light in the upper frequencies compared to my old QED Silver and Ortofon Copper speaker cables.
I have since tried them with the Antique Sound Lab monos, Quad 909 and my Croft Series 7 using identical sources both vinyl and digital. They certainly have improved the clarity and separation of the 909 which can sound 'muddy', lack tonal definition and position sometimes. However the whole valve/Hybrid sound is even smoother, more articulate with each instrument's position in the mix identifiable and the tonal balance improved. I think the bass depth has also improved with the mid range calarity and upper frequencies extended.
All in all, excellent value for money. Thanks to Marco and ColinB for recommending them to me