Playing Digital Music
Playing Digitized Music
Some products have USB ports that are controlled by a phone app. For example the Yamaha Aventage RX-A1070 and RX- 3070 receivers have a front panel USB port, and a controlling phone or tablet app.
Each Heos unit comes with a USB port. With the app, one can select the music at the album level, playing some or all tracks. If you have 3 Heos units in your home, you have live access to 3 USB ports. USB interfaces currently have a capacity of 32 gigabytes - approximately 40 CD discs.
If you wish to have access to a larger library, then you'll need to consider using a hard drive with a computer.
Audio Digital Servers
Many of the amps, pre-amps, and receivers have USB ports. But there is no app to control the music selection.
Connecting a computer as an "audio server, connected through the USB port, will provide full control. As you can imagine with the computer interface, you get many more features - for example creating play lists from many different albums.
The finest audio server is call Roon. The Roon Server can be operated without a display or keyboard - it's a feature they call "headless" server.
The computer automatically boots up, and an app on any of your phones controls the music. The music can be stored on the computer's hard drive, or can be played from USB memory drives. (A USB memory drive of 32 gb stores approximately 60 albums.)
The Roon app - running on a phone or tablet - allows you to browse and play music on all devices - Mac, Windows, iPad, iPhone, and Android devices as well as your audio system. Each device can play something different from the musical library.
Roon goes further - it enhances your music selection. If you subscribe to a service like Tidal (which streams CD-quality music), Roon combines your music with those that you "rent" into one huge library - exposing you to new music based on what you're listening too - without any advertisements.
Roon costs an annual fee of $119 per year.