Digital Optical Cables - how important is brand?


I am presently using an Acoustic Research optical cable from my Pioneer Elite DVD/CD player into a Denon DTS receiver serving as a preamp with a Parasound 1000 HCA amp.

Maybe this is a dumb question, but are their truly significant differences in optical cables?
I do use DH lab Siversonic speaker wire with my RBH Sound speakers, and also a Tekline RCA connector from my receiver preamp outputs to my amp so I do think that decent cables are desirable, but the optical thing kind of throws me.

Any opinions are welcome and suggestions of a low cost (sub 50-75$) optical. That is if better ones than my 20$ Acoustic Reserach really do seem to make a difference.

Thanks.
lkdog
Thanks for the responses.
Did a lot of reading last night and glass sounds like it gives people better performance, and the Sound Professional glass Toslink came up on several forums as a good choice for reasonable cost. I will give that a try.

Ok, one more question - what is a decent reasonably priced RCA coaxial to try so I can compare them?
My Pioneer Elite has RCA Coax out, and the Denon has both toslink and RCA coax in. I read the debates and many believe that coax is better, but there are pluses and minuses to each. I have also read where RCA connectors on the coax is fine, but not the ideal.

I know this is a modest system, but just trying to make it sound the best I can. Adding the Parasound amp made a huge difference and I am trying to optimize the other links.

Thanks again.
What I have read in some reviews seem to indicate a burn in of some sort by some manufacturers.
Hi Lkdog, I would recommend checking out the Bolder digital cable (with Eichman bullet plug RCAs) for your coax option. It's a very well made digital cable, it sounds excellent, and it only costs about $85. The Apogee Wyde Eye is also a great deal for $35, but I prefer the sound of the Bolder by quite a bit.
Phild- Thanks for the recommendations.
How would you describe the differences between the two?
I have a pretty neutral sound with my setup right now.
Is one more forward in a frequency range, or is the Boulder just that much better overall?