Thanks for all of your replies. I bought the Audioquest Vodka cable yesterday. 10% silver wires with silver plated solid copper connectors. I don't know of a WireWorld dealer here, so would have had to order, but your recommendations got me to try something new.
This AQ HDMI cable is better sounding than what I was using, which is something called a "Pipeline" formerly available at RadioShack, but that looks like an Audioquest Cinnamon HDMI, also purports to have solid rather than stranded conductors. And this wire had significantly better picture and better sound than the Auvio brand HDMI cable I have, also from RS.
As mentioned above, my other option for two channel sound out of my Samsung BDP is a medical grade glass fiber optical toslink cable. I noticed that I liked the sound of the Pipeline HDMI cable over the glass cable, a little smoother sound. I think Arcam went to some length to reduce jitter through HDMI connection to my receiver, and optical may be limited by the parts used to code and decide the optical signal on either end.
AB'ing the AQ Vodka with the Pipeline and optical cable here is what I notice. More low level and spatial information, more subtle details and little faster sounding bass. Treble slightly more extended but reduced sibilants in vocals and electric guitars. I can listen louder without discomfort (a good thing?).
My standard high resolution multi-channel test disk is the Blu-Ray of Crossroads Guitar Festival 2010. Listening to "Don't Keep Me Wondering" with David Hidalgo & Cesar Rosas with Derek Trucks I could play nearly as loud as I remember hearing Los Lobos in a small club without strain. Drums and cymbols were not lost in the mix. On the next cut Warren Haynes guitar sounded like it was coming from the right wall of my room. Great! The picture is above reproach as well, but not sure I can effectively AB that, since there is about 15ft of BJC HDMI cable between the Receiver and my Panasonic plasma monitor, so no serious attempt to resolve difference there.
One of my favorite two channel test tracks is the Branford Marsalis Band "Eternal" from the 2004 album by the same name. Lots of dynamic range on this cut with spatial cues in the drum kit and cymbols. Big difference here in quiet passages in how physical structure of music is presented in the soundstage, and I am noticing resolution in all 3 dimensions and breadth of the soundstage that I have only noticed before using the analog front ends on my current system. This is the most obvious difference that jumps out during 2 channel AB with other cables.
Why digital cable of any kind should make any difference is harder for me to grasp, but it does. I tried different off the shelf USB cables in my office computer based system and there was a noticeable difference in performance. As mentioned already I hear a clear difference between HDMI and optical in my system, with that difference exaggerated by adding the AQ Vodka HDMI.
For context, my system consists of a separate power line from the breaker box with a 20amp breaker and a 10 gauge supply line and medical grade outlets. Samsung BD-H6500 BDP set to stream raw PCM data to my Arcam AVR which is fed with a Shunyata Diamondback power cable. Speakers are Monitor Audio Apex A40s in front and Apex A10s in the rear fed with AQ Type 4 and Flex 14/4 bulk cable through the wall and a B&W PVD-1 subwoofer. Listening area is a dedicated custom built 18x12x8ft. listening and viewing room. So the HDMI cable I am using is more expensive than my current digital source used as a transport, but I notice a positive improvement, so there you go.
Thanks again for your recommendations. It spurred me to try a better HDMI cable. Very pleased.
