Is there any mini-jack converter for the Mac Mini

I think optical is the only other digital output, Mono price has cables with the correct terminations.

I also forgot to mention that there are devices on the market that will convert the USB output from your Mini to an RCA type connection. Trends Audio and Bel Canto both make this type of converter.

The Blue Circle Thingee will take a USB input and output coax as well. Of course you can always go digital out (mini toslink) to toslink in on your DAC if you have that facility. I've used both and preferred the Toslink, but that's just me :-)

van den hul makes a great glass toslink that can be had with mini to std toslink config. it's 100$. works great.

Also Tascam in the Pro-Audio world has a USB device that has SPDIF out. They can be picked up at most GC type stores. The last time I looked for one they were about $149.00. I believe the model number is US424.