which solder do you recommend?

I was taught that in soldered connections the wire should be firmly crimped to the terminal before solder is applied. Electrical contact is made without need for solder. The purpose of the solder is primarily mechanical, to prevent the connection from coming loose. It also helps with electrical continuity, but the current flow path is basically from conductor to conductor without going through solder. Where components are installed by leads through holes in a circuit board conductor-to-conductor contact is not assured and some very small distance of the circuit path is through solder.

In military electronic equipment that is designed to withstand nuclear weapon effects electrical connections are often made by "wire wrap". A special tool is used to tightly wrap several turns of soft wire under tension around a square post. Believe it or not this makes excellent electrical contact, and even severe vibration (as during missile flight) does not shake the wire loose. In the nuclear effects environment solder is a bad idea...it melts.

I have noticed that some higher priced solder is easier to use: has better melting characteristics.

Philjolet...New shiny wire, where you have just stripped away the insulation, does not nead cleaning. If there is any suggestion of oxidation on the wire clean it.

Flux cleans the metals being connected, and prevents the rapid oxidation that would otherwise occur while the metal is heated up. Solder is usually made hollow, like macaroni, with the flux inside. Very important...make sure that you don't use "Acid Core" solder. This is too corrosive for use in electronic circuits.

In modern circuitry the components and the circuit board pads (where the components attach) are very small, and it takes considerable skill not to botch a soldering job. In particular, you don't want to apply too much heat.

And yes...solder is part of the audiophile religon.

Herman...The intermingling of solder molecules and the wire material is a surface condition, and that's what makes the stuff stick.