Are you looking for some all-in-one thing with amplification and speakers or are you just looking for a streamer with an output that you'll feed to something else?
If the latter, you'll save a pile of money it you just buy a Raspberry Pi, equip it with the audio output card of your choice and install Max2Play software. That might sound like a lot of trouble, but it's really not. For about $100, you'll have a tiny little box that functions as both server and player. The only other thing you'll need is storage, which can be directly attached USB or networked. If you get a digital output, you'll be able to feed DTS and AC-3 to your receiver.
I'm not badmouthing Sonos, but there are some limitations to be aware of, one of which is how much it will take out of your wallet. There's also a limit to how many tracks it can handle, though for most normal people that's probably not an issue (it is for me, though). Having said that, I mostly hear nothing but good about Sonos' simplicity and reliability. As for DTS, I'm not sure. It's unlikely any self-contained device would work with it, but if their streamers have digital outputs, you should be OK.