Multiple stranded (MS) cables sound more detailed, deep, and focused (smaller sound images) with less sound stage and less bass. So, it is good for string and brass instruments and acoustics/classical music. Generally, MS sound makes feeling bright, excited, and happy.

Solid-core cables sound punch, more energy, and big/thick sound images and stage (the wall of sound) with more bass. SC cables are good for percussion instruments and Rock/fusion music. Generally, SC sound makes felling sad, and down.

We, cable designers, mix wires to make balanced sounding cables (and to sound close to the original music). To make a good cable, we need the best reference audio system to hear cables. A problem is all their audio systems sound veil and un-natural. The veil sound means the signal is broken and distorted and those systems can’t be a reference system. Sadly every audio systems in the world are sounding veiled and un-natural. In the land of blind, the one-eyed man is king. I only know what they are doing wrong. Alex/wavetouch

Check out Magnan speaker cables. This company has came out with a concept of multiple wires smaller than a human hair, in a flat-shaped cable. They sound pretty amazing and extremly neutral. For those looking for solid copper speaker cable I would recommend WhyNot speaker cables which are probably the best on the market. Both concepts have advantages and inconveniences and system matching is always an issue. To solve your dilemma, you should test both in your system and decide which one to keep. 

Duelund DCA16GA tinned copper multistrand wire in cotton and oil

Oops sorry for the font!

I've always made my own: lamp cord; common speaker wire; monster cable; solid strands of thick copper, stiff, hard to bend; cat 5 and now cat 8.

It's hard to know what you are convincing yourself about 'better'.

So, off to research, something's gotta be real:

What made sense, and what I settled on, is multiple individually insulated, small diameter solid core, i.e. Cat 5. Easy to make myself, flexible enough, put high quality connectors on. Small diameter reduces the 'skin effect'. Many say that's a joke at the lengths we use. Believe in Santa or not?

Now, CAT 8, Pure Copper, insulation for: each strand; each pair; 2 layers of outer insulation, whoopee. Looks cool, personal involvement is rewarding, Sound better?

I've never been willing to spend big money on cables. I've moved my friend's very expensive cables here, listened, better? Even he doesn't hear anything obvious here.

Based on all that, I would never use large diameter solid core again. There was definitely a dullness.

I do think experiences/results vary based on the efficiency of your speakers. Mine are highly efficient horns, 16 ohms (so amp is using 16 ohm windings). Perhaps I could/would hear real differences with different speakers.

I also keep my cables the same length l/r, even though at the lengths involved, many say that's absurd.