I haven't had any experience with the V2 Siberia. It was fairly popular back in the day, so I'm sure it's at least a capable performer for it's price. All I know is that I liked the SLYR for it's price range, if you absolutely need a headset, not a headphone.
You can also just spend $20 or so on a Sportapro, snap off the drivers, and attach it to the cheap Parts Express headband, which equals a KSC35. That is a VERY capable headphone for cheap, and I prefer it over everything else under $100 that I have tried. Look at the KSC35 listing on the guide. There is a video I posted explaining what to do.
Your soundcard I belive has Dolby headphone so you're good there. i believe those Xonar soundcards all have a headphone jack that doubles as an optical out (don't quote me on this) once you set the proper options in the software. Then later on, you can buy a cheap dac with an optical input (Fiio D03k), and a decent amp which will be a better combo than using the soundcard alone, though it's more clutter. I'd personally just save up for a used Fiio E17 or something which is both a dac/amp which you can attach to the Xonar soundcard.