The sound quality on my xps 15 speakers appears to be a little degraded. It would be very helpful if some one suggests a good audio driver package for ubuntu 12.04 64-bit.
I have 2.1 channel speakers.
and welcome to AskUbuntu.
It may sound unusual, but there aren't any special audio drivers for XPS15 and Ubuntu 12.04. Ubuntu is a Linux distro, and as such, it uses Advanced Linux Sound Architecture, aka ALSA, which is preinstalled.
I rather doubt there is anything to troubleshoot in your particular case. Most laptop speakers can only produce mediocre quality sound, and to improve the quality substantially would most certainly require external hardware. Simply plugging in a decent pair of headphones would probably be sufficient.