Onboard vs Cheap USB SoundCard? Options

[Tall-Guy]

Hey,

Up until now I have been using my Onboard Sound Card - ALC1200(Realtek). It suppose to be quite decent according to reviews (I'm mainly using it with Headphones).
More technical information about it can be found here.

Recently I purchased a set of new headphones that comes with a USB Soundcard: Steelseries USB Dongle. Technical information can be found here.

Few questions based on the above:
1. Is any one of them significantly better than the other (spec-wise)?
2. Does Onboard card getting Amp on the way out by the motherboard? What about the USB soundcard?

I tried to compare them using my ears, but the time it takes me to unplug and plug everything again (and change the output device in Windows) just takes too much for me to 'Remember' how to previous sounded. Or perhaps it just the difference was not that major for me to notice.

Thanks.

[Tall-Guy]

Brand,
Yes - I hardly believe I'll be listen to Music with max volume (I could hear the RMAA tests clearly when the headphones were on the table).

Garf,
Just as a reference, It was tested using a 32 Ohm headphones.

Below you can find the results with 'Optimal' volume. On the Speakers output the Max was optimal. In the Headphones out and the USB Card I tweaked it down a bit.
It seems like the USB Card is performing much better with volume at 2/3 than max:



Still, I'm assuming the Headphones Onboard port is still performing best?