The Bluesound devices are obvious choices but be warned that there seem to be lots of issues with syncing and them disappearing from Roon (I’ve had my fair share of issues with new Pulse Flex 2is and sent them all back). Next to the Airplay and Squeezebox options mentioned here, you could build a Raspberry Pi + HAT + passive speaker solution very cheaply, which seems the most solid option.
RPi 3 b+, SD-Card, Case ~50-60 USD
HifiBerry AMP2 ~60 USD
20V power adapter ~20 USD
Then get a nice pair of passive speakers and set them up connected to the RPi endpoint