Tonyangel is right (sort of). Sonos can only play files that are on the network. Files can reside on any computer folder as long as the folder is being shared on the network. Therefore, a USB hard drive will also work so long as it is visible on the network. The drawback to this approach versus using a NAS is that the PC tue USB hard drive is attached must be on all the time. Using a NAS also gives you automated backup. I am paranoid so I use a NAS configured to Raid 5 then use another NAS set up to backup my primary NAS once a week. I am also thinking about paying for cloud storage as well. Overboard I know but it has taken me 25 years to amass my music collection. I don't want to lose it all.
Hard drive for Oppo 105 and Sonos
I'm thinking of doing Sonos or something like it and want to start the process by ripping all my CDs to an external drive (that'll give me a chance to decide on Sonos or other similar system while getting the rips done). I want the drive to be compatible with both my 105 and Sonos so when I want I could use the USB connection direct to the Oppo 105 and also have the drive on all the time so it could be accessed by Sonos (if this is possible). What drive would make the most sense for my needs?