I did, and it works great. Here are the components I used:

- PSU : https://www.amazon.com/gp/product/B06XJVYDDW

- PSU mains power cord : https://www.amazon.com/gp/product/B07BQ8PY21

- DC power pigtail to connect Soundboks to PSU : https://www.amazon.com/gp/product/B08PYWN3T7

IMPORTANT: You can adjust the PSUs output voltage by 15%. Make sure to set the voltage to what the Soundboks is expecting from the Batteryboks (12.8V I think, but please verify before you plug in).

If you are still looking for a simple solution i have been using this combination for 6 months now, with no issues so far.

https://www.amazon.com/SJHPRMXF-Universal-Regulated-Switching-Transformer/dp/B09V7XF3Y6/ref=mp_s_a_1_1_sspa?crid=1VFWVXV3IAG7N&keywords=12v+ac+power+supply&qid=1682323385&sprefix=12v+ac+power+supply%2Caps%2C577&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzMDNBMVM2WlNGV0RXJmVuY3J5cHRlZElkPUEwNjEzMTY4MUlIQ0NXREJVN01CUSZlbmNyeXB0ZWRBZElkPUEwNjUzODg0M0w5TVRDME9DNllPJndpZGdldE5hbWU9c3BfcGhvbmVfc2VhcmNoX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

https://www.amazon.com/Pigtails-Female-Connector-Pigtail-Security/dp/B08PYWN3T7/ref=mp_s_a_1_9?crid=34O2544YQ0D28&keywords=DC+5%2C5+mm+x+2%2C1&qid=1682322646&sprefix=dc+5%2C5+mm+x+2%2C1%2Caps%2C830&sr=8-9

In theory the 30A ps covers only 1 speaker, due to peaks in power, even if i've never had any problem
running one speaker off a car cigarette lighter plug, fused at 20A. Still, i would buy 1 for each speaker since they are quite cheap. They do sell a 50A version but I have no experience with that.

So I would just buy a normal cigarette ligher and expose the wire? Or how would I do it?

What about something like this: https://www.amazon.com/Pigtails-Female-Connector-Pigtail-Security/dp/B08PYWN3T7/?pldnSite=1