You can store the files on a computer hard drive or NAS and connect to the music library through the Sonos app:

https://support.sonos.com/s/article/257?language=en_US
 

FYI… Sonos speakers only support up to 24-bit/48kHz FLAC files.

https://support.sonos.com/s/article/79?language=en_US

Thanks much for the response!  So if I set up a NAS, will the files that are encoded at 96kHz be downconverted to 48kHz and played, or will they not play at all?  Would I have to convert them to 48kHz first?

I’m pretty sure the files need to be downsampled to 48kHz or they won’t play correctly or play at all.

I’d agree. To my knowledge, the Sonos “Player” doesn’t have the ability to interpret higher bitrates, and do the downsampling, that has to be done first before Sonos gets involved. 

Here’s the FAQ on those requirements.