Bought a new headset and it sounds tinny?

[cooledwhip]

Hey all, I just bought a pair of Sennheiser Game One's headsets for myself this christmas. I need a good gaming headset for competitive counter strike and after upgrading from Astros A40's I thought I would make a switch so I bought a pair of sennheisers. Sennheiser is a reputable brand. I just put them on and have been trying them on and off the entire day, and the audio is kinda tinny. 

 

The sound is sort of echoed or tinny when listening to people talking or a LTT video (not on LTT's end it's the headset)

 

I don't have a sound card, my motherboard is a GA Z97x Gaming 5 motherboard and I have the 3.5 mic and headset jacks plugged in to the front of the case. Is the computer recognizing these as speakers or do I need a sound card? (I have no sound card) 

 

I know nothing about audio really and it was a big enough challenge building my PC. Lol, thanks everyone and happy holidays.!!

[SuicideAnomaly]

Before doing a full-blown diagnosis, try plugging it in to the motherboard directly and see if that makes any difference.