- Joined
- Dec 1, 2007
- Location
- Near Toronto Canada
One big reason is that USB works with laptops without the "phantom display" issue that sometimes affects HDMI used for audio only. Very few laptops have S/PDIF out. And most recently, smartphones are going with USB-C audio.
For home setups, HDMI is the most popular nowadays. Every amplifier with HDMI in I have seen also has S/PDIF for compatibility with older equipment. But very few have USB client. Much more common is USB host for plugging in a USB drive to play files on it.
Actually lately there are dozens of integrated amps with built in USB dacs. Computer as source is the future of HIFI. The feature is less common on A/V receivers as those are really meant for audio/video simulataneously with music as a secondary function.