I need some help here.
LAME has been working fine with EAC all along, but it gave errors when I wanted to compress wavs with mppenc or OggEncGT3b1. I had set the appropriate encoders in the external compressor window, and used the commandline --quality 5 --xlevel for mppenc, while set the quality of the oggenc to 6, leaving the commandline box blank. Can it possibly be due to the use of profiles (though it sounds absurd)?

Check if you have it set up like this:

http://www.saunalahti.fi/~cse/EAC/

hmm it works now....why must the external encoder be set to user-defined instead of the respective ones for the 2 codecs mpc and ogg? One doesn't have to do so for LAME.