In reply to:
can i use the analog 5.1 connections without using the DVD audio disc....is there much difference in the audio quality between regular CDs and DVD audio ??
Yes, you can, but there is no good reason to do so.
Just my opinion, but I feel there is a LARGE difference in audio quality between standard CDs and Hi Rez discs (DVD-A and SACD, which stand for DVD-Audio, and Super Audio CDs, respectively). But, both formats are like standard CDs in that some discs are mixed and mastered better than others. A well mixed and mastered SACD or DVD-A, to me, is goosepimply amazing.
Have you ever noticed the difference between music on a CD and the way music in a movie soundtrack with Dolby Digital 5.1 or DTS 5.1 sounds? If so, that will give you a good idea of how much better a good DVD-A or SACD can sound.