I can highly recommend the Pro-Ject S2 Pre Digital (it’s a mouthful).
I bought one for my old man (my dad) to use with his Sansui AU 4900 and vintage B&W speakers. He says it’s the best his system has ever sounded.
He’s feeding it with my ultraRendu and linear PSU’s though that I’ve let him ‘borrow’. Don’t think I’ll be getting them back though.
I played around with it at my place before installing it at dad’s place. Really impressed.
http://www.box-designs.com/main.php?prod=preboxs2digital&cat=default&lang=en
Instead of using the Mac as a source, I’d recommend the Allo USBridge to feed the Pro-Ject S2 DAC. In total it should be around $550 in total.
The USBridge comes fully assembled. There’s just config of the OS required but there’s plenty of support around this forum.