Thanks Marco, those YA spades are almost identical, right down to the little word stamped into the face. Except, mine have a stepped width inside, and the YA's don't. Similar in price, I paid just a little less, and would have paid the $5 each if I could have avoided the month wait from China.
Those speaker wires I've got, with Legacy brand name on them, when I bought my Legacy speakers second hand, the owner included these cables. They look expensive, but I've always thought he would not have included them if they were? I've tried to price them but they no longer make them, can't find anything on them. But originally came with WBT locking banana plugs. They have an impressive grip on the binding post that accepts them, and aren't cheap! But I like the fact that I can swap ends on these Legacy wires back and forth between the spades or locking bananas with only an Allen key.
The posts on the Krell are impressive, big wing nuts with a fat post, easy to get a nice tight fit with lots of surface area mating. But, I do believe they are brass. Pure copper would not be tough enough, the threads would strip right off, and the post would stretch. So I suspect that even these copper terminals you've posted here are copper plated something. Or a copper alloy that's harder than pure copper. Pure copper spades are more practical, if they deform a bit that's no big deal. And both copper and brass require a bit of maintenance, they do tarnish over time. A yearly cleaning wouldn't hurt them. I used to tear my whole system down and clean all connections, and open all components and clean the circuits and switches and knobs. A worthwhile undertaking, but I confess I've gotten lazy, I can't recall the last time I opened up any of my components, but I do still clean the connections every year or so.
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