So guys I'm buying this brand new headset from sennheiser I just wanna know about USB headphones,I have a good motherboard Asus deluxe x99 am I being stupid for buying usb headset and not utilizing this mb or is the built in soundcard on the headset is even better? Or should I keep the mb for a home theater if I want in the future!
not sure about the new pc373d but i'm familiar with the pc363d which is a bass light headset.
usb headphones include their own dac (digital analog converter) and amp (amplifier) and bypass your onboard or soundcard completely. quality level of the one included is generally mediocre. if you have good quality audio products like a soundcard, this is detrimental. if you have low quality audio products this can be beneficial.
the quality of high end onboard audio is about the same as low end soundcards like the xonar dg. what is included in usb headsets can range from low quality onboard to high quality onboard. at best i would say its equal and at worst i would say the usb may be slightly worse. should be somewhat comparable but i'm more apt to say onboard would be a bit better.
as for quality, you also had other options available such as using separate headphones and microphone. there are many great options in a similar budget as you spent.
regardless, a mid priced soundcard is still superior to both options. whether or not you can hear the difference really depends on how good/bad your current hardware is (if you hear any audio issues) and how good your ears are.