Yeah I'm less than pleased with the Head-Fi search algorithm, too.
As far as "what DAC to use with electrostatic 'phones" - well, I suggest using a GOOD one. Many many GOOD DACs out there. There are also some GREAT DACs and with a good amp and Stax phones you might hear the subtle difference between GOOD and GREAT DACs.
Seems to me the biggest differences in DACs are between sigma-delta DACs (Wolfson WM8741, ESS 9018) and R2R DACs that use PCM1704 and so on.
There are also various approaches to the circuitry that surrounds the DAC- the analog stages and the power supplies. These can have an impact on sound too. You see things like the Audio-Gd DACs which tend to use a large number of "Class A regulator" power supplies and all-discrete analog stages with selected / matched transistors.
Then there are DACs like the Lavry DA2002, which takes the trouble to tightly regulate even the temperature of the DAC components and has a method to self-calibrate the resistance magnitudes in it's R2R ladder.
Even though these "uber DACs" offer good engineering and fine sound, there are also a lot of modestly priced DACs out there that will sound better than the DAC inside your MP3 player / cell phone / PC. A used Cambridge DAC MAGIC can be reasonably priced; a MK 1 Musical Fidelity VDAC can also be gotten for very reasonable money and is a fine DAC for those who like a bit of "lush" sonic character voiced into their DAC. TONS of respectable DACs out there.