A couple of weeks ago I came across a 9to5Mac article indicating that Apple has updated all Airport Express 2nd Gen (A1392) firmware to 7.8. This means that if you have one of these little gems you can pretty well enable any active speakers or receivers that can take RCA, 3.5 mm, and optical toslink inputs (with appropriate cables).
I immediately scour my local Kijiji site and Facebook marketplace for these devices. I ended up buying five of these little devices. One for $25 CAD and the others for $50 CAD. All are in working order and I added all five of them to my network, enabling all of my speakers in the house. Now every speakers on all three floors in my house are AirPlay 2 enabled.
To test the new setup, I ended playing Christmas Carols on all three floors. The songs are all in sync. As I walk around the house, it is pretty surreal to have the same song omnipresent around your head.
The boys are happy because their bedroom speakers are now enabled via AirPlay. This means they can be more lazy by switching songs while laying in bed. Before, they had to plug their iPhones into their receivers.
If these devices are still around, you cannot beat the $50 value to enable any speakers of your choice to be AirPlay 2 compatible. Start looking around!