Speaker cables

There is definitely one company that makes a barrier strip-to-spade lug pigtail adaptor (it's called a Spealunker):

http://www.angelfire.com/biz/bizzyb/spealunker.html

$30 for a set of 4. Good luck. BTW, these are meant more for bananas and plain wire, but I think they should work OK with spades if you're careful.

I assembled an adapter for my vintage Fisher tube integrated from plexiglass with off the shelf 5-way binding posts and wire. It works perfectly though maybe not as elegant as the item Nsgarch shows.

My friend bought those but didn't like the construction.
There are alternatives from Cardas CCMS S and
Philmore 45-282G ( with stright wire and banana plug adapter.)

I check on the Spealunkers and was told they work with bananas only. The ones at Audio Classics look well made, cost $149+. Cards will put on spades that work with the barrier strip for $100.00.