the digital to analog convertor..
the speaker output quality..
the microphone input quality..
the amplifiers that drive the microphone and the speaker..
every single step is a potential disaster.
a premium digital to analog convertor is enough to drive the headset up to like $700
seriously.
there are usb digital to analog convertors that have insane prices.
ranging from $180 to $10,000 ?
headphone audiophiles go crazy with the products they make available.
but let one not forget..
a specific model of digital to analog convertor can be paired with a specific headphone speaker to work together as a team and form a more solid result.
you might go with that theory, but either one is a gamble.
maybe the dac and the headphone speaker is perfect, and the amplifier is junk.
headphone audiophiles talk about premium digital to analog convertors quite a lot.
since they sell ONLY the digital to analog convertor that plugs into the usb port.. it should provide proof that soundcard or usb is a question of not the jack, but the hardware connected to the jack/port.