Soldering, if done properly, is about the best method an individual can use in terms of lowest resistance... Soldering is also electrically very reliable, but doesn't necessarily have the best mechanical strength.... but soldering also has the greatest chance of
NOT being done correctly and, in fact, many people who think that "they know how to solder" really don't. In contrast, crimp splices have been designed to be more or less foolproof if you follow the directions. (Use the correct crimp tool; use the correct crimp splice for the gauge of wire you're using; squeeze down until the ratchet in the crimp tool closes all the way, then releases by itself.)
I would also caution folks that a lot of the "rules and guidelines" you may read about for "proper soldering" are for specific situations, and many have changed over the years, for various reasons.
For example, many of the new fluxes are specifically designed to be active at elevated temperatures, but inert at lower temperatures, and so are intended NOT to be cleaned after soldering. However, other fluxes are quite active, and will corrode the connection if not cleaned thoroughly afterwards (which means, rather than using "a little alcohol", they should be rinsed multiple times or even soaked to remove every trace of flux). Also, the new RohS compliant, environmentally friendly, lead-free solders, and the fluxes that go with them, are much more difficult to use and get good results with than the old style SN63 lead/tin Eutectic solder used in virtually all electronic equipment before RohS. (And a lot of the instructions written for that solder don't work well for the new type.)
I'll give you an interesting example of how the rules differ depending on the application..... To solder a wire to a terminal, the general instructions are to tin the wire, wrap it around the terminal, then solder it. However, the details vary depending on the application. In military applications, it is generally recommended that the wire "should be wrapped at least three quarters of the way around the terminal to ensure a good mechanical connection before soldering". The mechanical wrap adds strength to the solder connection, and, even if the solder connection fails, or someone forgets to solder it, you still have a somewhat functional mechanical connection. However, in
VERY CRITICAL military applications it is often specified that the wire only be wrapped around the terminal 1/4 turn or less. The reason is that, in certain applications, it is considered preferable that
ONLY the solder holds the wire in place - because, in those applications, it's better for a poorly soldered wire to fall off and fail "hard" than for it to maintain poor contact, and cause intermittent problems that are harder to find and repair.
In general, if we're talking about speaker wire, and you aren't an expert at soldering, your best bet is indeed to use a crimp splice.
And here are a few tips:
1) always use the correct sized crimp for the wire you're using (they are usually color coded)
2) always make sure to crimp the splice all the way - it's better to pay a little extra for one of the ratcheted crimpers that won't open until you close it fully
3) always pull on the wires afterwards to make sure you actually crimped the wires (it's possible to get a tight crimp where the wires still aren't properly held in the crimp)
(a good crimp splice is strong - if it pulls apart when you tug on it, then it
WASN'T good).
4)
DO NOT solder a crimp
5) use
BARE STRIPPED TWISTED COPPER WIRE - crimp splices are
NOT intended to be used with tinned wire
6) if you have a wire that's tarnished, scrape it, or clip off the end and re-strip it
(the wires should be
SHINY; if they're dull or dark then you may not get a good connection)
7) if you strip the wire, and the strands that were inside the insulation are badly tarnished, then you've got some
REALLY bad wire -
DISCARD IT
(ditto for wire with clear insulation where you can see that the wire inside is dark or oxidized green -
THROW IT AWAY)
8) most crimp splices have an outer plastic insulator; on some of them the outer plastic is heat shrink
(so, after you crimp them, you use a heat gun or lighter to shrink the plastic around the wire....)
9) for extreme conditions, you can get heat shrink with adhesive on the inside; it shrinks to a waterproof seal when you heat it
(there are even crimp terminals with adhesive-lined shrink already on them.... very cool)
10)
AVOID electrical tape if at all possible; heat shrink is better; tape falls off, slides around, gets all nasty and gooey
(there are some fancy tapes that shrink, or fuse in place, or stay stuck very well; heat shrink is
STILL better)
11) When using heat shrink, be careful with the heat; some wire has insulation that will melt at the temperatures used to shrink heat shrink
(and different types of heat shrink require different temperatures; if you're not sure about your wire, then don't buy "super high temperature" heat shrink
)
)