Spades terminations into spring load trminal

As others have said, the "half spade" into the terminal wil work but not very well. It really is a "kludgy" way of doing it.
If you do not want to modify the cables, I like the option suggested by Hifihvn best. The problem is that the spring contact counts on the deformation of the wire to create a good contact surface. The solid pin will not deform and you are left with a very small point of contact. It is better than sticking the spade in there, but not by much.

Really, the best connector is no connector. Cut off the spade and stick the wire into the terminal. That connection will be electrically and mechanically secure.
hth

These plugs from monoprice might work, depending on the size of your spade terminals. The pins are designed to work with the spring terminals you have and the back of the plug unscrews. If the spade is wide enough to fit over the inner barrel of the pin plug you'd have a secure connection.

The third picture of the plug shows the relevant construction.

Straight pins do not work well on spring loaded connectors designed for bare wire. The only thing that works right is bare wire.

I have been using something similar to those shown by Sfar. I have some older Boston speakers in my bedroom with those pesky spring loaded clips. I bought the plugs at radio shack. Good luck and happy listening.

I agree with Rrog that the spring terminals are designed to work best with bare wire but if you don't want to remove the spades, which seems sensible if you want to preserve the resale value of the cables, the pin terminals are the best option I've found.

Even if you cut off the spade terminals from the cables you just bought there's a very good chance the gauge of the bare wire will be too large to fit into the spring terminals. I wouldn't argue that you couldn't hear a difference between bare wire and the pin terminals but I've never been able to.