Is O2/ODAC overkill for casual gaming?

I'm tired of the shitty gaming headsets that's available out there. I've been trough SteelSeries Siberia V1, Siberia V2, Siberia Neckband, Corsair HS-1, Corsair Vengance 1500 and the Logitech G430.

The Steelseries Siberia has decent sound, but the plastic is really squeaky - on all three models I've had. I actually like the sound in the Corsair Vengance 1500, but the build quality is very bad. Both off my Corsair headsets broke within the first year - and I did some repairs on them to make them last longer. The Logitech just sounds horrible. 

I saw the tek syndicate video of headsets below $50 and am currently looking at the Superlux HD-681 evo + a ModMic. However, I am quite concerned that my motherboard can't deliver the power the headphones need to perform. I have a Gigabyte Z77n-Wifi with a onboard realtec ALC892 chip.

I started reading about the O2/ODAC and that seems very nice, but suddenly I would be spending three times as much on the O2/ODAC as the headphones and mic combined. 

Would it be overkill for a casual gamer (a few hours FPS a week) to spend that much money on audio? Besides the gaming I only watch some movies and TV shows on the computer - I almost never listen to music. Would I be better off with the Kingston HyperX Cloud (II perhaps)?

How would the O2/ODAC be connected? Is this correct? :USB -> O2/ODAC -> Headphones and Mic In -> Mic

Is there a O2/ODAC design out there, where I can plugin headphones and mic in the front and all other wires go out the back?

There would be an improvement, but I don't think it would be worth the price. In my opinion, it would only be worth it if your headphones cost the same, or more than the amp/dac (not counting shit stuff like beats).

Honestly, you probably wont need a headphone amp unless you want to listen to music. I say this because I used the Superlux HD 668B without an amp as well as with an amp and the only difference between them is that the bass is reduced and the overall volume is slightly lower with no amp. However, if you are set on getting an amp, you could either build one yourself (or get someone else to build one for you) or buy a less expensive amp than the O2. (For example, you could make the Cmoy amp)

I agree with Tazuna. With something like the Superlux HD 681 you won't need much at all to power it. Your onboard audio will work with them, but an amp will make it sound better. The bass will be fuller and the audio won't sound as weak across the board. For amps you can get a CMoy from JDS Labs for like $60 or even the Schiit Fulla, which is a DAC/amp combo unit, for $80. Or if you don't mind soldering you could make your own CMoy for $25. An O2/ODAC or Schiit Stack will be a waste of your money unless you are in headphones for a lot of your free time.

If you're a casual gamer you won't notice much of any difference from a DAC though. I only own a DAC because I listen to a lot of music, but at $100 I almost regret the purchase. They do clean up the sound, yes, but does it sound $100 better? Not really.

In short, DACs aren't worth it unless you love audio, amps are nice but not required, and CMoys are a great bang-for-the-buck amp.