Fiio BTR3k is a Bluetooth receiver, usb dac and headphone amp. It will most often be used to power a wired earphone or headphone and connect by Bluetooth to a phone. It can also be used to add a quality Bluetooth connection to powered speakers and as a usb dac for a computer. High quality built in mic and 11 hour battery life.
Fiio BTR3k has all the latest Bluetooth connectivity codecs: it has AAC (mainly for iPhone), apt-x, apt-x HD (many new android phones and its very good), LDAC and LL (low latency, so the sound syncs with video/skype calls).
The BTR3k sounds better than basic Bluetooth receivers since it takes the signal from the bluetooth chip and runs it through a 2 higher performance dacs to drive the headphones. This provides a clearer and more powerful sound.