Depending on your needs, the Audix TR40 at half the price of teh Earthworks may also work for you. SIA offers both on their web site store. I own an ACI MP-400 and consider it an essential part of any Smaart system. It's got the right hooks to make system measurements easy to set up. It's a little pricy but other options require at least two boxes plus a bunch of cabling.
Many solutions are also quite large.
EQ referrs to the system equalizer. Push the level controls in to defeat them for calibrated measurements. Info on the web doesn't explain the box very well, and the manual is only a tad better. To be truly useful, they should both be stereo. That way you could leave it in the system path at all times.