Trying to use a preamp for a MC cartridge

I recently went out on a proverbial limb and purchased a EAT MC cartridge.  I knew that it would need a phono preamp and have now tried two brands, both with the same result, load distortion of the lp.  I have a Marantz SR 5014 that has a phono input.  It works well with a MM cartridge.  I am going from the turntable, to the preamp and then into the phono input on the receiver.  Am I doing something wrong?
If you truly bought a phono preamp, you'll need to connect that to a receiver's "line in" stage. If you bought an MC step up device - such as a transformer or head amp - then that should connect to a phono input.
As @cleeds said, if the cartridge/tonearm cable is connected to a phono pre-amp, the phono pre-amp should be connected to any "line-level" input on your receiver, not into the phono input. 

The phono input on your receiver is for directly connecting a MM cartridge/tonearm cable to your receiver. It has a phono pre-amp, i.e. Gain and RIAA equalization built into it. If you connect a second phono pre-amp into the circuit you are going to over drive it.

So yes, you are doing something wrong.