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

Wyred4Sound has come out with a $400 mini DAC. If it is a giant killer like the DAC2, it might be the one:

Wyred4Sound MDAC

With a bit more research you'll find you don't want the DAC to do the upsampleing unless it has defeatable filters, not likely at this price point. Upsampling can be accomplished with playback software such as Pure Music.

All the connectivity features, and kHz numbers are simply fluff compared to the quality of overall design and resulting sonic quality of the DAC's output. It's not unusual to see people using an $1800. USB to SPDIF converter with a $700. DAC

The Schiit Bifrost is actually a very good, if not currently one of the best, suggestions at this price point.

http://www.digitalaudioreview.net.au/index.php/audio-reviews/digital-source-reviews/item/330-schiit-bifrost-24/192-dac-akm4399

HRT Pro, or Musical Fidelity V-DAC might work for you. Saw HRT on" Gon"
yesterday.

Check out a Music Streamer II by HRT

I was in the exact same position as you a couple months ago. I bought this:
http://www.ebay.com/itm/Valab-WM8741-24bit-192k-USB-DAC-Dual-WM8741-Balanced-XLR-Output-Black-Face-/300703596949?pt=US_Home_Audio_Amplifiers_Preamps&hash=item460354c195
Dual mono, excellent build and parts choice. Inputs all formats and plays all frequencies. I am very happy... Note, USB is the tenor 7022L, usb only does up to 24/96 and is not Asynchronous. I did add a USB to SPdif that was Asynchronous and had galvanic isolation...
In your pricepoint to get it all, the Schiit is an excellent choice and after having an upcoverting DAC, I have come to believe that playing native resolution is better.
The entry W4S looks great and the Peachtree iDAC has great reviews.