I stream audio via bluetooth to my Raspberry which is attached to my stereo.
Now, I'd like to have the same without bluetooth with IP only. (Basically to save the 5€ for a bluetooth dongle for a PC by investing hours in software configuration instead ;-)
But Wifi should have a higher bandwith than Bluetooth, so I think audio quality should be better.
Clients would be Windows and Android.
There is this old thread from seven years ago. Is ShairPort and Tuneblade still the way to go?
Audio quality will be the same - as the network transfer is not the limiting factor. If you want better audio quality, you should invest in a DAC for your Pi as the standard audio output is known for poor quality. However, this is likely to cost many times more than a cheap Bluetooth dongle!
That aside, you can send audio from one Linux host to another Linux host over TCP/IP using pulseaudio. However, it seems you want to send from Android or Windows and pulseaudio is not well developed as a client on these platforms. If you are using Spotify as your source, you may find that you don't need to directly send audio from a Win or Android client and you can use Spotify Connect instead - https://github.com/librespot-org/librespot - which you can control on both Windows or Android.
I haven't been able to provide you with exactly what you need. You may find this guide gives you the inspiration you need to reach a solution that does what you want: https://mathieu-requillart.medium.com/my-ultimate-guide-to-the-raspberry-pi-audio-server-i-wanted-introduction-650020d135e1
