This is written by Jon Risch and in the FAQ section at Audio Asylum:
*How should I terminate my speaker cable?
First, if all your amp/receiver has those spring loaded terminals, there are not a whole lot of options. The gold plated pins that are available for such connectors are not an improvement over a good bare stripped wire connection. If you have spring loaded terminals, save your money and forget the gold-plated pins, use the bare wire, twist it hard and tight, and insert it naked. If the total wire thickness allows, double the wire over, and jam the doubled-up wire into the terminal opening, you want as much spring pressure on it as possible. I do not recommend tinning such a conection, and if you have some disposable speaker cable length, about every 6 months, cut off the oxidized exposed bare wire, and start fresh.
Those of you with gold-plated heavy duty 5-way binding posts, the choice here is clear: gold plated spades, preferably properly crimped. If you can not make a proper crimp via a crimping tool, then a proper solder joint will be very close in quality to a good crimp. Amazingly enough, the gold plated spades offered by RS are OK, one of the few RS parts I can recommend at all. The very best spades are the type with compression washers built into the spade fingers, such as the WBT and the Kimber Postmaster spades.
After spade lugs, the next best connection is a gold-plated expanding/locking banana plug. Standard non-expanding or non-locking banana plugs with a nickel plating are not very good at all, nor are the cheap gold-plated kinds at RS. Monster and WBT make the good types of banana plugs. "
Here is another post By Jon Risch answering the question: Why Terminate solid core copper wires?
"Copper is very soft, expecially very pure copper. Hand tighten a bare wire ESPECIUALLY TWO TWISTED TOGETHER, and the contact will not be optimal.
Try tugging on the connection and see if it mnoves or can be made to come loose. If it moves or comes loose, then it is not tight enough.
In order to tighten down hard enough to assure a good contact, a lot of pressure should be used. The only way to do this is to have a hard base metal, brass or a copper alloy, and have a nice soft gold plating over this to smash together with the binding posts (which hopefully also use gold plating). Spade lugs crimped to the cable are ideal for this. Tighten as much as possible by hand, and then use a pliers to go just a little further (too much and some chaep binding posts will come loose, etc.)
Hand tightened bare copper, EVEN solid wires, just are not a good clean contact. Forget stranded, and don't even think about tinning them, this is the worst!!! "
