If you don't mind the sound of Delta Sigma conversion get one of these used, Flying Cow Midiman 24bit A-D or D-A converter, mine cost $100
Here's a new one
http://www.ebay.com.au/itm/M-Audio-Flying-Cow-24-Bit-XLR-Analog-AES-EBU-S-PDIF-Digital-Analog-Converter-NEW-/331690997254?hash=item4d3a52f606:g:C4sAAOSw0HVWBxTT
Cheers George