Hi Kian,
I recently did this and it went fairly well in the end. I had a PMC centre speaker that I no longer used so decided to create a Roon Speaker out of it. I used a Pi and IQAudIO DigiAMP+
This has the DAC built in and I used Diet-Pi mainly because I was familiar with it from two previous builds. There is now a GUI version of Diet Pi or you can use an image downloaded from IQAudIO or Ropieee as alternatives. You can read about the issue I had at this thread, and how with the help of fellow Roonies I fixed them:
I sent a mono signal to the endpoint as the speaker has a split crossover. So one channel fed the tweeter and the other the woofer for a 30+30W active speaker.
Check this thread for how to send mono to the endpoint: