How to get the best sound quality out of this great phone?

I bought a Samsung captivate from a friend yesterday. He was running Kitkat on it and it is very slow. My only use of it as a phone is recieving calls and text messages, nothing else like facebook,whatsapp or anything. My main use for this phone is to use it as a portable music player as I travels alot. I saw an old thread from head-fi that, this phone can be transformed into an Audiophile level music player using a Voodoo kernel and an Voodoo control plus App. But that was in 2011. What is the current situation? How can I get the best sound and best battery life out of this great device? I mean, which rom or kernal or modes to get the best sound quality out of this phone?