For anyone interested. My $500 budget squeezed out of my wallet, and turned into a $900 mini-DAC. Why not Duet? Well, several reasons:
1. Duet won't work if my MacBook fails me, and my MacBook does indeed do freaky things now and then. That is also why I chose FireWire and not just plain (optical). The mini is in other words far more versatile as far as source goes - which many of you here, including the Duet fans, pointed out.
2. Some of youse had problems with the Duet, like when Time Machine set in.
3. The mini-DAC has a dual clock, and should therefore be more independent on the quality of the optical signal. It also has an upsampling of the incoming DC, and is in a way therefore also very independent of the PSU quality.
4. Larry (HeadphoneAddict) told me about the sigma-11 and the advantages of a PSU that delivers ample quantity of current.
5. From your described differences in sound quality in different threads between the mini, the Duet and the DAC1, the mini's "warm" quality sounds like the perfect match for my preferences + cans.
But that is of course not the end of it. I also bought a pair of MD5000, and have my eyes (and money) on a Cowon i7, a pair of RS-1, and some IEMs for the treadmill ... probably Atrio M5 if I believe they will fit my ears.
What's more, I am now on the prowl for a proper amp ($2000 class) to buy in a couple of years. In a couple of years, guys, for I am truly broke now! This site is indeed a dangerous place.