Actually, holland makes a good point - perhaps the simplest DAC to DIY is the SkeletonDAC. Yes, I sell it. I'm not shilling, but rather essentially confirming that the SkeletonDAC is the current implementation of the AlienDAC. The BantamDAC was next after the Alien - basically an AlienDAC shrunk down with TPS regulators instead of REG's, but using the same PCM2702 chip. As time went on, the PCM2702 became NRND from TI - Not Recommended for New Designs. Because of this, the price started climbing for the chip so that it equaled the former cost of the entire kit.
Cobaltmute was kind enough to design a low-cost follow-on DAC based on the PCM2704/5, TI's stated replacements for the PCM2702.
Before you say the specs aren't nearly as good as the PCM2702, I'm not sure I ever saw anyone achieve the specs that TI quoted on the PCM2702. I think there may have been some funny business going on in the early days of testing DAC chips. For whatever reason, the Bantam/Skeleton seem to be fully equal to the Alien, but of the three DACs today - only the SkeletonDAC is still available.
I try but some words I can not understand (my english is very bad) :(
I do not quite understand what is the best dac ... All these dac's names are better than my asus xonar dx? and would have a better result with my amp o2?