Need a quality external soundcard / amplifier for headphones

[Cheesetogo]

I'm looking for a good quality external soundcard for use with headphones. Since these will be used on several computers, and it's obviously not a viable option to carry around a PCI card everywhere. (Not to mention one of the computers is a laptop)

I came across this HeadRoom Total BitHead in a review, and it seems really nice, but I'd like a few more opinions and options. Also, I'm wondering how this would compare to my X-Fi XtremeMusic that I use in my main computer.

My budget would probably not exceed the $150 that this costs, and ideally I'd like it to be closer to $100.

Thanks in advance for any comments.

Edit: The headphones I'll be using is the Sennheiser HD555.

 

[corkyg]

I don't know anything about the BitHead device, but I have used the Creative USB Audigy 2 NX. This seems like a successor to that, and is worth a look.

External

Here's my old 2NX - it works very well and can drive headphones or speakers.

2NX