Thanks to both of you for your help. I had almost completed a reply before having to leave for an event, and it all seems to have disappeared so I think what I said was as follows:
1) Yes, I can see (and access) the NAS drives in File Explorer (and I could at the time of trying to configure MB). That was the first thing I checked, just to make sure that they network wasn't down or some other issue like that. Should have mentioned that.
2) I tried to point MB to the mapped NAS drive (mine is using Z:), but they neither showed up as regular letter drives or at network drives that could be added.
3) I should have clarified that I only mentioned the SONOS usage because if I had to change the NAS from a mapped drive to a network share, I wasn't sure if that would affect the SONOS connection. It was probably a poor choice of words to say SONOS streams. I just meant that it's working well with the NAS as it is configured now.
The reason I thought I had to move away from the mapped drive is from the last comment on this thread:
https://getmusicbee.com/forum/index.php?topic=22839.0I would greatly prefer to leave the NAS as mapped drives much as you both say works fine with MB. That said, I now have to figure out why MB won't/can't see the NAS.
Thanks again.