Cables for high efficiency speakers?

Well if you want the best chance of getting all the detail and treble energy your system can deliver, than the best objectively measured conductor is indeed silver. If so I can recommend a medium priced pure silver cable by Homegrown the Silver Lace.(not really cheap anymore as silver is going up,up,)
If perchance you wish to hear a good pure copper conductor do it's thing. I like the pure copper braid by JENA labs. The intro level trio shouldn't break the bbank. I think it might yield a more balanced overall presentation.
Good Luck.

I would also add a vote for TRS cables by Coincident I have heard them on Coincident speakers and they are excellent at retrieving low level detail and have excellent dynamic capability. I am not sure what the recipe is in terms of the wire's metal or gauge. I should note that I have heard them on other speakers and their performance is obvious. As for price well they are not easy on my wallet.
I want to add that StanWal's preference for Cardas copper is one that I also share but in a different application. There is no doubt however that it is excellent cable.