I have no experience with audiophile quality soundcards, but I do have the TBH. Soundwise, the TBH DAC has a smooth and somewhat dry sound. Compared to "bigger" amps (e.g., HR-2 or Headroom Supreme), the TBH is less dynamic and less detailed.
I'm not certain if the TBH's internal DAC is an essential feature even with my "stock" laptop soundcard. I've tried connecting the TBH straight to my laptop's headphone jack (thus bypassing the TBH's DAC), and found that the sound is also quite good. Using the TBH's DAC vs TBH analog-in yields different sound rather than better sound. On the DAC, music is drier, darker and more relaxed. On analog, the TBH is a bit brighter and punchier sounding. Personally, I prefer the DAC sound. I reminds me abit more of my HR-2. Analog sounded closer to the Supreme.
However, I must say that connecting the TBH via USB - which engages the TBH's DAC - does save batteries and reduce desktop clutter. The TBH feeds off your computer's power source and there is no need to attach an adaptor to the amp.
In my opinon, the TBH's DAC is better suited for jazz, instrumentals, some vocals and lighter music. If you like music with more speed and slam - rock, hip-hop, techno, etc. - perhaps you might want to check out some other amps (or use the TBH's analog section).
Of course, keep in mind that I'm using a home CDP for the HR-2 and Supreme. The TBH is used exclusively with my laptop.