I'm a new Sonos user and really never thought to have researched the aspect of the system supporting high-res files. I'm sorely disappointed to find out that it doesn't.
Personally, I'm a jazz-buff. Many recordings, with the best remastering, are only available in either a high-res format or alternately mp3 (yuk). Basically, I don't want to have to play around with my new downloads. I just want to copy them over to my library and be done with it. Why in the world would I want to do otherwise? This has to hold true for users who don't have techie backgrounds and don't want to have to ferret through processing their downloads to a smaller resolution, just for Sonos. This will hold true regardless of what ever sampling theorems are out there. People just want their stuff to work without problems and issues! I have a music library of over 2,000 recordings. I really don't want to have to figujre out how to covert recordings to a lower-resolution, glean through over 2,000 of my albums, find the high-res ones and then convert them all.! There are many music buffs that will have the very same issue.
At this point, I believe that the real problem is that the speakers don't have the computing capacity to reformat audio files to a format that they can really process. This would explain a lot. Also, it might be why we don't hear of this problem with other speaker manufacturers.
I feel that if this really is going to be Sonos' stance, they should really open up their product to 3rd party developers. If they did so, things would really take off.
The whole Alexis thing sounds great, but this needs to be resolved.
In the end, I don't really see how Sonos' current stance regarding high-res files does anyone any good, including Sonos.