Can I use 24 gauge speaker cable?

It is a little too thin.

Probably not suitable for an amp with more than 10 watts/channel output.
When the wire is too thin, its resistance will be relatively higher and its stray capacitance tends also to be higher. This would limit the current flow and affect the high frequencies negatively by attenuating them.

If you have an amp with any power output greater than about 10 watts/channel, you should probably use approximately a 16 gauge wire. Having said that, you do not have to buy any esoteric expensive "audiofool" wires. Any ordinary pure copper wire (NOT copper clad or aluminum) will do. Just make sure its capacitance is as little as it can be.

All in all, you should not need to spend more than 30-40 bucks on it, AT MOST.

This would do PERFECTLY for example:

https://www.amazon.com/KnuKonceptz-Kable-Gauge-Copper-Speaker/dp/B006VP97DE/ref=sr_1_4?dchild=1&...

or this....

https://www.amazon.com/InstallGear-Gauge-Speaker-Wire-Oxygen-Free/dp/B01MQVETL7/ref=sr_1_1?crid=3A20...

#24 AWG seems to be thin. 5m is long.
Front or rear speakers?
to get the front speakers cable thickness I need your Amp's Damping Factor (DF).
Then I can calculate the thickness (AWG) with the 5m length.

Cakyol has his head on completely straight and seems to be grounded in the laws of physics. I use 24 gauge wire for one of my systems with a 3.5 watt tube amp and high sensitivity vintage (Frazier) speakers - it sounds incredible, top to bottom. Generally for higher output, I would personally go with a larger gauge - BUT nothing fancy or expensive. I have been very happy with the high quality, flexible Installgear wire from Amazon (Cakyol’s second link) on my main system (a more beefy McIntosh tube system). A friend of mine with 40+ years experience and some of the best sounding gear you're ever heard, goes with 14 gauge wire from Home Depot.  Hell, if it was good enough for the iconic Paul Klipsch, that's good enough for me.

williewonka, and several other of these bloviators for that matter, on the other hand are marinating in snake oil. PLEASE don’t get sucked into the "cable science" nonsense (non-science)! All auditory hallucination paid for with obscene amounts of money and bolstered by clever marketing designed to steal your cash. And don’t bother to argue with them - predictably, they’ll now attack my system, hearing, sophistication, credibility, etc, with zero science to back up anything they try to put forth. Just put them on mute, move on, and enjoy the MUSIC.

Once again, the forum shows that some people can hear differences with thicker wire, better interconnects, etc while other people either can’t or won’t. This is not meant as a diss, but rather than query the Hatfields and McCoys on this, why not buy (if you don’t already have some) a couple of different gauges of wire at the Home Depot and listen for yourself?

Better yet, if you can borrow several different manufacturer’s speaker cables instead of raw wire, compare those as well. That way, instead of relying on someone’s opinion of what you can or cannot hear, you’ll know...

Totally agreed @tbakin63. Of course it looks kind of awesome to have these cables worth 1000’s of dollars but it’s nothing more than jewelry. If Mr Klipsch (and other highly regarded people in the industry too by the way!) says it’s not worth it to spend a lot the I believe them.

My current cables are quite nice looking Dynavox cables, 4 x 10AWG wires inside. But they’re also quite huge. That’s why I’d love to see some smaller cables in my house. So why not go with the smallest cables I could find at the Home Depot, i.e. 24 AWG? :-)

Next week I’ll have the chance to play around with a 3Watts/channel tube amp. I’ll be testing the telephone cables for sure! I just wanted to make sure I won’t melt anything or set stuff on fire :’)