I started out using the spade lugs that terminated my speaker wire, but my wire was heavy and stiff, and it had a tendency to loosen easily when bumped or adjusted in a counterclockwise fashion that would loosen the nut. I've stripped nuts on other speakers and am hesitant to really tighten them down a lot. I switched to Monster Cable X-Terminators, a spade-to-banana adaptor that let me use the banana sockets on the Proac nuts. The X-Terminators are designed so that they can be tightened in the socket after insertion. After I moved the speakers to another installation, I switched to bare wire basically as a matter of convenience. I haven't had a corrosion problem, perhaps because our air is pretty dry. I haven't noticed any real difference in the sound with any of these terminations. (Obviously, the change from X-Terminators to bare wire occured as the speakers were moved to an entirely different room, which could easily overwhelm any termination-based differences in sound.)
