Terasic Data Conversion AD/DA bandwidth

I am considering the following two daughter cards:

http://www.terasic.com.tw/cgi-bin/page/archive.pl?language=english&categoryno=67&no=278&partno=1

http://www.terasic.com.tw/cgi-bin/page/archive.pl?language=english&categoryno=73&no=360

Both of these cards have balun transformers to couple differential and single-ended signals on both the DACs and ADCs. What is the attenuation for low-frequency signals?

Also, where can I find the reference manual for "Highspeed AD/DC card" ? I only see a User Guide.