You must be kidding with me right?
NO
To say better or superior is exacly the same thing c´mon... (You wanna play semantic games is that it? i don´t get it...) If the card has more features that doesn´t make it better/superior?
NO
Along with more expansion capabilities, ST also has a better clock circuit than STX so it would sound better
PROVE IT. YOU ADMIT YOU DON'T EVEN HAVE THE CARD!. If you go to check on Asus website you can confirm that ST is "World's first Precision Clock Tuning for Revolutionary PC Hi-Fi audio"...
I don´t have one right now,
SEE WHAT I MEAN but I have read to many opinions and reviews, from well reputeted websites (like Guru3D for example), and I even created a thread here, asking for some advices, because i´m going to get a sound card for me. And as you can see, i prefer ST over STX.
THAT'S WHAT I WROTE BEFORE, IT'S YOUR PREFERENCE
Edit: Here you have a text trascription from Guru 3D´s review (for example):
[size=x-small][size=x-small]"The New ST's main feature is the new pin header which allows the card to connect to the H6 DAC expansion card which can currently be seen bundled with the HDAV 1.3 Deluxe.[/size][/size][size=x-small][size=x-small] THAT IS A FEATURE THAT APPEALS TO THE HT[/size] AUDIENCE, BUT DOESN'T MAKE IT BETTER/SUPERIOR TO ONE WHO ONLY DESIRES 2 CHANNEL STEREO, DON'T YOU READ MY POSTS?
[/size][size=x-small][size=x-small]With the addition of this pin header the new ST has more diverse repertoire of features and output audio options available to users.[/size][/size][size=x-small][size=x-small] FOR THOSE HT TYPES {Between the STX and the upcoming ST, the Xonar sound machine will become much more diverse for headphones users and high end speakers users alike.} THIS IS EXACTLY THE POINT I'M MAKING
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To comprove "Precision clock tunning" go to Asus web page (you can do that...). And if you still have doubts read some reviews.