You suspect; I know ! How significant? only by dint of an incontrovertible improvement in dynamics and all that goes with it. A recent speaker cable bake-off involving 7 people incl. a classical music lover dealer were present. With a specific track from a good master of a 'Living Presence' Danse Macabre, 4 different cables were tried. NAC A5 plus 2 others and a True Signal (American?). Wadia CDP into E.A.R. 899 into the latest Quad ESLs.
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Dear Mike,
I know that there are differences. I was being meek!
But, I also know that slight improvements can be made at a budget level, even on speaker wire.
In the old days, when I had Naim amplification [90, and later 100], I used the stock NACA 5 cable, which is unwieldy at best. When I went to Quad [valve] amplification I decided to change speaker wire. After all second hand NACA 5 is an appreciable monetary asset that it would be idle not to exploit.
I asked Quad at Huntingdon for their optimal speaker wire recommendation between the amplifier and an ESL. They gave me a specification and not an actual recommendation. I found out the specification of the normal highest grade Maplin speaker wire, and asked Quad if that would be fine. The reply was that it was a proper match and would certainly work better than NACA 5. And it did! Not by a lot, but certainly enough to find that the sold NACA 5 covered my new six foot length of Maplins cable price by five times! Quad gave me a couple of banana plugs for the speaker end and and I used the binding posts on the amp directly.
I am not really sure that I would have concurred with your group test though in preferring a speaker wire that made the system more dynamic. I am assuming that you mean "macro" rather than "micro" dynamic, but I do find that even old style recordings have sometimes too much dynamic swing for domestic use. So I would not want to expand on this aspect personally, even if I could perceive it in a test.
Best wishes from George
PS: [Edit]. The improvement I perceived with the Maplin speaker cable was also down to dynamics and clarity. Overall the cable was less weighty in the bass, which was a delightful relief, as even a single ESL can make more bass than I would want at home. But in reducing the perceived bass by a small margin the Maplin wire also reduced the macro-dynamic effect slightly, while concentrating the effect in the middle voices, where subtle musical balances and vital micro-dynamics were made all the clearer and musically involving. So the Maplin wire was bringing out the qualities already associated with the ESL 57 type.