I have a rooted note III that I have been using as a music player (errr... phone....) for the past several months coming from an iPhone 5 and I could not be happier. I am using USB Audio Player Pro with a Meridian Explorer and a pair of Sennheiser IE800's and this setup is pretty close to my audio nirvana sitting in my office all day It could be widely known, but the addition of a powered USB hub was a neccessity for me since the Meridian chewed the battery life of my NoteIII very quickly. Since I have added the hub, I can listen all day without problem. The hub also allows me to plug in a 2tb drive filled with my flac collection.
Okay... enough bragging about how much I love this setup and back to work lol.
consider getting a wireless charging back plate or insert for your note 3. i have that for mine, and i use my phone to usb otg out to my HiFi-M8 all day at work, and when i leave, my phone is at 100%.
In fact, since I've gotten my Qi charger insert and bought a few Qi chargers throughout my home and at my desk at work, I rarely see my phone go below 50%. This also affords me the ability to leave all my syncing options on, as well as GPS and brightness at auto or full brightness depending on the situation. I even use my wifi hotspot (unlimited data which i am grateful for) for my home streaming of netflix, etc. The wireless charging takes the "how is my battery life?" thought out of the equation!