Ethernet Cables, do they make a difference?

A dealer explained that upgrading an Ethernet cable ONLY helps if you run it through a splitter box (any one will due). 

Ultimately, these things have to be tested with one’s ears. The guy who is content with just a lo-fi iPod should stick with that (even though even he would hear a difference when compared to hi-fi). 

I read all the controversies, then groked a solution for steaming MQA files ... relocate the DSL modem (80 Mbps service) directly next to my PS Audio Directsteam DAC then try various 1 meter ethernet cables.  

Started by drilling a 1/2" hole directly though the wall from inside my DSL wall box outside of my house and ran a 5 meter Blue Jean cat 6 cable directly to the modem.  Understand this DSL modem input cable is hardwired from the wall box using only 4 wires to a RJ11 connector (Phone plug) on the modem. Surprise, Surprise ... a noticeable improvement! Further improvement when I switched to a 4 wire individually shielded twisted pairs with 22 gauge silver plated solid copper wires. Even more when I used a 12V Lithium Ion battery to power the DSL modem. Crazy, fanatical ... I think not, just standard logic folks.

With the modem now optimized it's easy to hear the difference between the various ethernet cables when steaming MQA.  Hell it even sounds better when my wife streams her mp3 Classic FM radio station from London. I'm not kidding, the entire house fills with classical music, before it sounded like a mono car speaker.

I can easily state that optimizing your modem is equally as important as your choice of ethernet cable. 

I tried both a 15M Audioquest Cinnamon and Tera Grand Cat 7 cable from Amazon to connect my optimized DSL modem to the rest of house. Small but noticeable improvement over my Blue Jean Cable wired house. I suspect fiber optic is the way to go for whole house optimization but I won't be sending that kind of money.

If you are following my bouncing ball, for fun I compared the long runs of Tera Grand & Cinnamon between the modem and Directstream DAC ... nothing special. Diamonds rule on this short thoroughfare.

@billallen10  +1  and a helpful post. Thank you.

Did anyone do a blind test?
Please post your honest results.
It would be nice to see “placebo effect” eliminated.

Do not get me wrong, I love high quality network cables and connectors, but I make mine myself, use high quality cable and connectors and cut them to the length. Why? Because I can and it doesn’t cost me much. Otherwise I’d use cheap cat5, because there is no any network need in the house requiring network speed that cat5 cannot handle.

Thanks to all!!
I did some research on the Net, and bottom line there are definate differences between my CAT6 and a CAT7 cable, basically, shielding individual twisted pairs and whole cable braid shielding. Also, not all CAT7 cables are the same, most boasted 10GB/s @ 600Mhz, but I found one that claimed 10GB/s @ 1000Mhz, there are also stranded and solid core cables. The claims about CAT7 were fairly consistant, in that due to twisting and shielding of the wire pairs and overall cable shielding the potential for noise being introduced in the signal is reduced. How this may improve Streaming SQ has yet to be determined. So, I decided on a CAT7 solid core 10GB/s @ 1000Mhz 10' run for $8 (shipping cost me as much as the cable). I looked at the AQ Vodka and can not understand what makes this cable cost over $500 for a 3M run! There must be something I'm missing here. I will A/B the new $8 CAT7 against my CAT6 and report back my perceived results. By the way, can anyone help me understand the difference between a 600Mhz cable compared to a 1000Mhz cable? Thanks!!