I've got an old pair of Infinity Studio Monitor 120s. They've got spring clips. Would it be possible/worth the hassle to retrofit 'em with real connectors?
Sure, I did this a while ago to one of my old B&O speakers, that just had bare wires hanging out the back!
Just go to your local electronics store, and pick up whatever connectors you want for your speaker connections. Then depending on the old connectors, you should be able to unscrew them, and cut the wires. Reattach the wires to new terminals, mount the new terminals, and you are all set!
Grand total cost, maybe 10 bucks if you went all out.
Maybe not. With a lot of speakers with spring clips, there are no wires between them and the crossover board. They are mounted directly to the crossover. If this is the case with your Infinities, you would have to de-solder them from the board and add the wires where the clips were.
This may well mean you can’t re-use the old connection panel, so you may have to fabricate a new one to mount the new binding posts (or whatever connectors you use) to.