A used dCS Delius - ~$2k without FireWire - can be fed direct by either toslink, rca, Aes, or Bnc This affords some freedom to experiment with interfaces, giving the option to go direct or through a converter. Personally have strong experiences with lynx hd26 to aes ($800) and empirical audios off ramp 3 (USB to Aes,$1k), but you might well find a mac using toslink works for you.
Also dcs has an excellent guide to computer audio on their website, within their support section, www.dcsltd.co.uk/page/support
If you do go this route, strongly recommend that the Delius is running the latest firmware