You should listen to both if possible... a low-grade analog stage supresses transient response, for one thing.
Apparently there is a way to mod the 1820m's op-amps and improve the sound. I've seen there is a forum over at head-fi.org where this has been beat to death about the 1212m, its little brother.
Anyways, even after this mod I would be stunned if it sounded as good as an Apogee converter. If it sounded as good as a Lynx Two... well... that's possible.
there's a discussion about the converters on it here: Emu 1212M Soundcard: Good?
I know this doesn't answer your question directly, but I said all I have to say in that thread.