If you want adequate power, get something based on the TK2050 chip. Output varies depending on implementation and (especially) the power supply, but 15W or so with 8 ohms:
- more reviews at Parts Express,
- Internals, seem reasonably built
If you want features, there are some that have DACs built in, which may give you a better sound quality (depending on how much noise your regular audio line out has).
- about 8 clean watts from the 2024 chip, enough for nearfield / desktop but not across the room
Of course, you can try an amp-only model with a regular line out from the computer and add a DAC later if you find the line is noisy on your setup.
Another option with that chip (the best known Tripath chip, but underpowered IMO), may have slightly better build quality than some amps:
While a little harder to find, reportedly the Indeed / SMSL amps have better build quality than the Lepai, Dayton, etc. which IMO don't meet minimum standards (unless there's a very tight budget). Too many problems with parts or calibration.
Or go for a compact conventional amp - 50W:
You'd need to give a budget, or your preferences for build quality vs. dollars spent, to get more specific advice. Eg, there's stuff like this and more, with better build quality and design:
http://www.amazon.com/Nuforce-ICON-AMP-BLACK-Stereo-Amplifier-Black/dp/B002YDYIW2/Edited by buzzy_ - 8/17/13 at 9:11am