I recently bought the new Play:5 and tried to connect it to my TV using the 3.5mm audio jack. I am happy to report that there is virtually no delay and the audio quality is a HUGE boost compared to the TV speakers.
If your TV (or other streaming box) does not have a 3.5mm audio out, you can use an HDMI audio extractor and an RCA cable . I am using this setup with my Nvidia Shield TV and it works flawlessly.
I understand that this may not be the optimal AV setup for audiophiles, but it is a great alternative for many who may not want to spend on expensive AV systems.
Play:5 for those that don't know what OP is talking about.