i would trust sennheiser as they make actual headphones for hifi use. with that said, there may be better options then the 363d for you.
i suggest listing a budget.
the 363d is a very bass light headset loosely based on the 555/595 and pc350se and also similar to the current game zero. not a bad can but dont expect a whole bunch of bass.
the game one is based on the hd518/558/598 series and has a little more bass and neutral sound. another option is to just buy these seperately and put your own mic like the modmic on a pair if the price is a big difference. game one and hd558+modmic prices were similar last i looked so game one may be a fair deal on its own.
if you're looking at low bass high soundstage headphones dont forget audiotechnicas ad500x->ad900x series. you wont find larger soundstage in that budget and they have the same light on bass sound. the adg1 headset is based on this but its double the price it should be considering the headphones used (modmic +headphone suggested instead)
if you wanted something with more oomph.. the dt990 from beyerdynamic has a v-shaped signature with substantial bass for an open can as well as detailed bright treble. its a fun sounding can with great comfort though given how bright and detailed it is on the high end some may find it fatiguing if they dont eq the treble down a bit.
do you need an amp or soundcard? generally no unless you are using high impedance headphones or note an issue with your onboard like buzzing, static, etc. headphones like the dt990 i'd certainly suggest an amp for. the old 100ohm game zero doesnt work well on all onboard (weak onboard audio = bad).
as far as 7.1.. its all pretty much faked anyways. in other words, virtual surround sound. generally you have 3 options.. razer virtual surround free software or the better sbx/cmss3d (creative soundcards and onboard) or dolby headphone (asus soundcards and onboard). any stereo headset can be made into surround with said software. only a few high end headsets use actual multiple driver technology (true headphone surround) but honestly that is not as good as it sounds on paper (its disjointed and fake sounding and not better than virtual)