Bare wire is SUPPOSEDLY best. This takes into consideration that the metals being used ( wire material and speaker terminal i.e. binding post, spring terminal ) don't react to each other. Dissimilar metals tend to corrode quickly. To help protect the wire from corroding, you might treat the wire and the terminal with something like Caig Pro Gold Liquid. This supposedly cleans and treats the metals, minimizing oxidation.
As to using some type of connector, a "real" crimp is supposedly superior to soldering the connector on. This would be "preferred method #2". Soldering the connector on is third in terms of a good connection. Crimping and soldering is supposedly fourth. I take this from information presented by Jon Risch on AA and others that are pretty well versed in things of this nature.
Having said that, i prefer to crimp and then solder any type of connection. You have to make sure that all the connecting surfaces have been properly prepped and cleaned, crimp the connection using a REAL crimping tool, use good quality solder, allow the solder to completely flow into the joint, let the joint set up and cool ON ITS' OWN ( no blowing on it to help it along ) before moving or disturbing it, etc...
Here's why i do this: crimping makes a metal to metal bond between the connector and wire. This assures low resistance. Soldering the connection seals the joint from oxidation. It also fills in any gaps and increases the surface area that is making contact. All bases should be covered if done properly.
The argument against soldering is that most solder is not very "pure" or a great conductor on its' own. That is why i crimp first, as this makes the basic connection and does not rely on the solder itself. Besides that, i see NO "theoretical" losses since there are HUNDREDS or THOUSANDS of solder joints in the signal chain. If someone was truly worried about the poor conductivity of solder, i would HIGHLY suggest re-flowing all of the connections on the circuit boards of each component using a high grade solder.
If you are not used to soldering, always use a THIN solder. You can always feed more as it melts and is needed. On the other hand, using a large diameter solder can tend to cool the solder joint / solder tip too quickly. This can end up in a high resistance / low strength connection that look poor and is not secure. Some good solders that i have used are Wonder Solder and Cardas. I find that Wonder melts easier and flows better. The Cardas requires higher heat and a little more attention. Supposedly, Jena Labs states that Cardas is the best sounding solder ( in their opinion ). Silver Bearing solder is MUCH harder to work with and not for beginners by any means. Common "generic" solder such as Radio Shack will work, but tend to degrade much more drastically over time. It becomes brittle and can become resistive as it gets older. Kester is a good alternative to this without costing an arm and a leg. The "no residue" solders that i have tried worked like junk, so skip them.
I think that much of the differences in the various formulations are not so much the metals used to make the solder, but the actual rosin. Keep in mind that you should never use Acid core for electronics unless you want a big mess with potential damage to components. Hope this helps. If you have further questions, try doing a search over at AA. Sean
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