Why lessen the contact area by crimping only?
If you're building an amp, or any electronic project for that matter, you don't just crimp the wires and leave them--you solder. Why? You get better contact.
If you only crimp, you are lessening the contact area to the termination. The termination's job is to present a wide contact surface to the amplifier/speakers/whatever. This is why some people like spades over all else--they have more contact area than bananas or bare wire.
Even if I use bare wire (which I do on my budget office hifi) I tin the ends. In my experience, this gives slightly better performance as well as protecting against oxidation, which is a MAJOR reason for sonic degradation of contacts. This is also why all terminations are gold/rhodium/whatever--to prevent oxidation.
If you don't tin your ends, cut a few inches off the ends and re-attach. You will hear a sonic difference!!