The UK shop that stocks Schiit doesn't have the Modi anymore so it would be the modi2 I would need to get. I've also been told USB is better than optical but I've no idea if it's true.
I've been told by different people very different things. Some say stay well away from sound card because there all very poor quality compared to dac/amp and others have said sound cards are great for gaming.
I was also told if I have a good dac/amp and headphones it will give better positional direction in stereo than a surround sound sound card is this true ?
Being able to use the sound card features might help with FPS gaming.
and while gaming your not going to be closely analyzing the audio quality, if there is even a noticeable difference.
Also you can have Windows set the S/PDIF optical to bypass the sound card features (in the Playback tab), to get a slightly cleaner digital signal, for while listening to music.
Technically you can get better audio quality going with an external DAC/amp, but sound cards are really almost as good, for a given price range.
My $300 external DAC/amp is only slightly better then my $200 sound card.
I've heard other say they prefer to use USB over a sound card for FPS gaming.
You might try asking about a gaming setups (DAC/amp/sound card), on these threads.
http://www.head-fi.org/t/534479/mad-lust-envys-headphone-gaming-guide-5-31-2015-beyer-cop-and-shure-1540-added
http://www.head-fi.org/t/593050/the-nameless-guide-to-pc-gaming-audio-with-binaural-headphone-surround-sound