Speakers for the TheC64 (Maxi)

There are HDMI audio splitters that provide usually a 3mm audio jack. I use my C64 mini or Raspberry pi with a HDMI to VGA dongle (only costs around $10) so I can plug them into an older VGA monitor. The dongle has a 3mm audio output jack, so I use a cable to then route the audio to a 1980's era boom box I originally piped my real C64 and Amiga's audio to back in the day. The boom box only has RCA style left/right stereo audio inputs, so for the C64 mini or Pi I use a 3mm to RCA adapter plug. In the case of my original C64 computer back then, since it wasn't stereo, I used a single RCA mono to dual left/right RCA speaker plug to mate it to the boom box.

For your situation, if you don't have a boom box or something to plug it into, I would just get some desktop PC stereo speakers to use. If you go to Goodwill or other thrift stores you can often find these for $5, and often they're from the 1990's to early 2000's.

Crazy but usually pc speakers or boom boxes from the 1980's to early 2000's have better sound than anything from the modern era such as Bluetooth speakers, mainly because stuff today is built in China as cheap as possible, where back then companies like Fisher put pride in their products.

Come to think on it I'd opt for a boom box from that era over PC speakers because you can use the boom box for other things too. I have a tiny Bluetooth receiver I plug into mine for doing things like taking it camping and playing music. If you're handy with a soldering iron you can even solder in a USB rechargeable lithium ion battery to replace the 6 or 8 D or C cell batteries these old boom boxes used when not plugged into a wall outlet.

PC speakers of that era are a great choice too though, especially if you don't have enough desk space to dedicate to a big boom box sitting behind your C64 mini or maxi.