Why do you want to use spades? Every mechanical connection, be it splice, crimp, or solder, creates an interface that the signal must cross, adding resistance (maybe capacitance..its been along time since E school) and detracts from the signal. Unless the laws of physics have been changed, a direct bare wire connection may not look as tidy, but seems to me to be the best. I suspect this is liable to start a debate.
Speaker Posts
In my 12 years as an audiophile audiogear lover, I have gone through over a dozen speakers. Not one has binding posts that fit well with speaker cables spades!! Ive spent nervous hours trying to expand and bend speaker spades so that they make a nice fit into the binding post. I only hope that one sunny day comes where speaker designers and speaker cable makers have a world summit to get it right once and for all.