This is a timely subject for me. I've got an RPI4 kit on order which will be delivered Tuesday. To date, I've been using an ultraRendu running Squeezelite, connected via ethernet to a small computer running Logitech Media Server (all music files stored on its internal HD). I use iPeng as the user interface. The uRendu is connected to the ADI-2 DAC via USB.
I've actually been quite pleased with how this has all been functioning but, lately, some software updates have rendered the ultraRendu unstable. By that, I mean that when I put the ADI-2 Dac in standby, the connection been the uRendu and ADI-2 is lost and, in the process, seems to crash the uRendu's webserver rendering the web GUI unusable. The only way to recover is to pull power on the uRendu and reboot. I sometimes have to do this two or three times for it to "take". Up until now, this rarely occured.
So, I decided to do an inexpensive experiment to see if I can replace the uRendu with the RPI4 running PiCore/Squeezelite and, with more ability to configure certain aspects of Squeezelite, I'm hoping to get more stability without sacrificing any sound quality. If so, I'll attempt to sell the uRendu.
I'm quite certain that if I can jump through all the hoops to get the RPI4 system up and running and talking to both the server and the ADI-2, and have the user interface still controllable via iPeng, that the RPI4 will perform it's streamer/player function every bit as well as the uRendu. I'm no techie, but I am persistent and I suspect the process will be frustrating and, hopefully, ultimately successful!! Will keep you posted.