Since your music is stored on the NAS, you definitely need some type of network connection out there: wired, wireless, or power line adaptor.
Power line adaptors are hit or miss and you must be on the same "side" of your local transformer, some surge protectors defeat them, etc. Ethernet cable is limited to 100 meters (less in the real world). There are ethernet "extenders" using POE but that drives up the cost and complexity.
Wireless from a decent router/repeater works for a pretty good distance with direct line of sight and no obstructions. I have an older ASUS N router set up as a repeater here on occasion and it does 150' into the back yard very well. I recommend getting one with external antennas, do your research, or borrow one for a test. Even a $30 unit should do the trick unless obstructions/line of sight is an issue. You may be able to daisy chain them if needed. A good wireless N or better connection should work with most if not all of your music, barring DSD, multi-channel high res, etc., IMO, if you are playing them lossless (unconverted).