I'm confused about "regular" radio stations I find listed as SONOS Radio "stations".  Are these streams coming to SONOS Radio via,a direct connection to those stations' own "streams", or is what I hear as a "SONOS station" actually coming from an intermediate connection, such as TUNEIN?  

Specifically, the local public radio station here is KUAF at 93.1 FM.  Because it broadcasts using HD Radio, it has 3 different broadcasts going on simultaneously via its 93.1 FM dial location (i.e., 93.1-1, 93.1-2, & 93.1-3). 

I enjoy listening to KUAF's Jazz broadcast via 93.1-3.  Using SONOS Radio, I can listen to it via the SONOS Radio "station" designated as KUAF-3; OR, also via SONOS Radio, I can select the TUNEIN station, then play KUAF-3 from TUNEIN.  

In 2 rooms, I don't have a SONOS speaker, so in those rooms I play KUAF-3 via TUNEIN on my Android phone through Bluetooth speakers.  

Often there's a very brief time difference (maybe a second or 2) between what I'm hearing in the different rooms. I thought that suggested that SONOS is just rebroadcasting the TUNEIN signal. 

But sometimes what I'm hearing as the "SONOS Radio KUAF-3" broadcast through my SONOS system is either WAY OFF (timing-wise) or sometimes it's even an entirely different song than what I'm hearing at the same time through the Bluetooth speakers in an adjacent room playing from the TUNEIN App on my Android phone.  oI can't remember hearing much difference when it's the TUNEIN access via SONOS Radio, however.  

Can anyone explain this?  

Thanks,

Paul