Any good quality DAC in $300-400 price range?

Thanks Mofimadness for your quick response.
I did a little bit of research on Schiit BiFrost and found that it doesn't do upsampling as others normally do. So it may not be the one I'm looking for.
Has anyone heard Cambridge Audio DacMagic 100? It seems to be quite interesting. Not sure about the sound quality though.

Thank you all for your great answers.
After reviewing everyone's answer and doing additional research, I've found that there are not many USB 2.0 DACs that support all of the available sampling rates. However, I think I'll have more options to choose if I get an S/PDIF connection. So I was searching for an affordable PCI sound card that supports various sampling rates and found ESI Maya44. Has anyone used ESI Maya44 sound card for S/PDIF connection? What's the major difference between USB to S/PDIF converter and PCI sound card with S/PDIF connector?

Thanks Timlub for the Musiland DACs info. Yes, I've heard about the Chinese brand and good quality of their products. It seems to be pretty popular in Korea too. (I've read the article on a Korean website.) Since I'm a PC user (for audio stuff) who uses Foobar2000 for FLAC files playback, I should definitely try it!