Digital Audio Cable

Just got my system. Magnepan MMGs Denon DVD 1600 and Denon AVR 3803. Love it so far.

My question: I have it set up using the three plugs to the reciever and three to the dvd but the instructions also says that I should connect an Optical Digital Audio Cable between the reciever and the dvd player. What difference will this make? Will it make cds sound better? If the system is already working is it worth getting? thanks
By "3 plugs" do you mean component video cables? if so, this is only Video information, and you need the digital 5.1 sound information to get from your DVD player to your reciever. That is what an optical or coaxial digital cable is for...
The digital cable allows the surround-sound processor in the receiver to be used for DVD's and CD's rather than the cheap one in the DVD player. Try it, It will probably sound better.
Thanks for your help. Two questions:

will this make any difference in two channel stereo?

Do I have change any of the settings or will the dvd/reciever know that there is already a wire there?

you will need a coaxial digital cable for your system, and don't use optical, unless you have no other choices. at this point i really don't know how 3803 dac perform, i have a denon avr 4800 and really their dacs is not so good, so i would say better stick with a digital cables it will sound better in 2 ch too. might wanna try cyberlink copper that cable sound ok for the price

I'm having a similar problem. Best I can tell for you it wont make too much of a difference (for 2 channel listening that is). It depends on which component you want to do the DA conversion (which one has the better DACs). If you're curious, just goto circuit city and try the optical cable (disconnect the others). From what I understand (and I'm not 100% on this) COAX is better then optical (romyus). I think it has to do with the manner in which the signal is transferred. the optical changes the digital to another code with must be changed back. The coax remains unchanged during transfer so you sacrifice less. (I could be off on this). FYI, coax cables are orange and look like RCA jacks- the 3 you have connected now - you may not have one.)