I use an asus xonar d2x sound card and a pair of beyerdynamic dt990 pro 256ohm headphones and the sound quality is fantastic. On board sound doesn't offer the sonic range and clarity of a dedicated sound card like this one. When a person runs low quality headphones and/or speakers then the sound card will not make much of a difference.
yeah but, is it even true?
because this explanation always annoys me. for high but-not-extreme quality audio you will want a standalone music system, not a PC, and either double-thick vinyl or at least a SACD as source.
Does your xonar come close to that? it doesn't. so let's stop calling your xonar a "superior solution" with "great soundstage" or all that other bullshit high enders love so much.
you are on a pc; you will be using some crap 128bit mp3 for 99% of your audio, your xonar doesn't do squat there.
when you use FLAC on the other 1%, what you have at best is difference, not quality. fire up a ALC1150 or even a 889 and they are easily comparable to any soundcard, at least in quality - they only miss the preamp, which some boards now include as well.
and finally we need to talk about reproduction. i've hear deutsche grammophon double pressings out of a $55k system, in its own purpose-built listening room, and while they sound great, they don't sound like a reference monitor, and a reference monitor sounds
exactly like the music that was recorded.
this is because people and companies that manufacture hifi chose to color the sound, sometimes to a signature tone, sometimes out of personal preference. or they might color an amp to highlight the strengths of a cabinet.
all that talk about warmth is bullshit. if it sounds different than it sounds on a reference monitor, it sounds wrong. so your "higher quality" soundcard is playing out a sound which can only and ever be accurately described as "different", and since you paid for it, you assume it's better (and i hope you do, because all humans do this - if you don't, you need to get checked by a head doctor).
integrated audio is fine. i can hear the wooden flooring on EMC's Keith Jarret plays Mozart@320kb mp3. it's fine.