So you recommend the U7 over the X-Fi HD?

Also to add on to my OP, thoughts on the Sound blaster X-FI HD vs the Asus Xonar U7 for gaming? 

Hello.   I recently purchased an Asus Xonar U7 for gaming/music/movies in that order.  I have Sennheiser g4me one headphones (50 ohms). I'm not sure if the xonar is damaged but the sound is atrocious compared to my ~7 year old internal sound blaster card.     My question is do I RMA it or do...