USB DAC's ?

I don't understand your ? since you have a dac in your pre.

You can buy a toslink cable that will connect the mini to the EMM. An 1/8 inch toslink to standard tosink. I use one to connect my mac to my dac.

On most of the Macs the headphone and mic jacks are combo jacks that make them toslink in and out

Hope that helps. Louis

Auditioning Vinnie's (Red Wine Audio) new NOS non-up sampling/no over sampling Isabellina DAC in my system along with Mac-book laptop as the source lead me to believe that it is in fact possible to achieve very good results with PC. The Pace Car from Steve (Empirical Audio)is also very promising. Short encounter during 2008 CES proved that this guy knows a thing or two about digital.

My main concern is the digital glare and usual edginess of digital file that is all so common these days. Even from highly regarded brands and products that are considered the "high end"

From what I have heard with my own ears, the above mentioned - accomplished very difficult task of music reproduction that I can connect to and enjoy.

I agree - your question doesn't make sense: Are you looking for ways to connect a Mac Mini to your Emm Labs DCC2?

Well, the Emm Labs DCC2 is DAC so why not just connect the Mini directly as Lbmp suggests. Or get a HagUSB or Emirical Offramp to convert USB to SPDIF and use that to go into your DCC2 DAC.

YOu don't need a DAC from Wavelength or Benchmark. You need an interface to get from USB out from your mini to a digital format your Emm Labs DAC will accept. This would be perfect and on the cheap. http://www.trendsaudio.com/EN/Index.htm

You might want to try out a Blue Circle Thingee between your Mac and your Emm Labs DCC2. In my experience it works well between mine and a Bel Canto DAC2. It's a good sounding and very flexible unit. Here's a review .......
http://www.goodsound.com/equipment/blue_circle_usb_thingee.htm