Originally Posted by HothBase
I'm afraid that some of the money you've spent on your setup has been a waste. Like someone already said, your Titanium HD is no better than on-board at outputting optical. There's also no such thing as the best optical cable as far as sound quality goes. A $100 cable will never sound any better than a $20 one. Same thing goes for HDMI cables and A/V quality. Digital data isn't affected by degradation during transport the way analogue is.
Regarding optical vs coaxial audio out, given that both are S/PDIF, I'm pretty confident that they sound identical.
Edit: Fixed wording (see the following posts).
I first owned the Titanium HD for use with the ULTRASONE PRO 500. It was only after I went true Hi-Fi that I decided to use the HD for my Optical. Some guy who helped me pick out my setup told me to buy a USB to Coaxial converter that cost $1000 to get rid of any jitter; I figured I should instead give my HD a shot first, and it sounded great to me. It's true though it sounds similar to onboard but I like Audio Creation Mode and bit-matched playback. I use CMSS-3D a lot too.
As for the Optical, I am in no position to test out different ones and return them. I did I a lot of research on the subject. I found these two opinions and went with it for my PC and PS3. Once they broke in, I love the way they sounded and have no regrets. That second link also discusses optical vs coaxial and I gathered info. from them too.