Your soundcard i fine, stick with it until decent USB3 cards come out and you have a lappy that has USB3 on it - should be noted that USB3 is still about a year off.
How do you figure that the soundcard is ok? I see only one stereo output and the headphone out. Do you know for a fact that the headphone output is not just a mirror of the main output (wich is often the case)?
Well, I can’t help with the buying in the store. The Numark I/O is probably a good place to start, and I’ve seen them around in Guitar Centers and Sam Ash locations.
I don’t think that would work, DJFar. The headphone port is only for monitoring, which should mean that it only will play whatever is coming out of the master channel. Therefore you can’t cue.
Just spend the extra $20 at a guitar center on the Numark I/O. The shittier the equipment the shittier everything works.