Euterpe is a music streaming software you can run yourself. It will give you access to your music everywhere you go. Either via its built-in web UI or via any of its clients. You could run it on your home computer, laptop or on a deticated server. Think of it as your own personal Spotify where you have full control over everything. It indexes your music and gives you convenient and fast access to it. You could search for particular tracks, albums or artists. Or you could browse them as if you are in a music store.
It is open-source and free to use for anyone. This means that you could avoid any subscription bills to streaming services. But best of all, you could finally listen to the music you personally like and own. You will not be limited to whatever the current-flavour-of-the-month subscription service has available. Your favourite album will not disappear because a record company did not sign a new contract with a tech company. The music from the obscure local artist you heard at a small concert and then bought a CD from is just as valuable as the one produced from a mega band with international record comapny behind its back. Now both could be everywhere with you!