I agree with you about the Empeg sounding a bit "dead". I have been told that its by design for it to sound flat...but I think it sounds flatter than flat. I think it sounds kinda dead...and I haven't been able to make it more lively with any EQ'ing. I don't think it has anything to do with the MP3's. I think it simply has to do with the quality of the analog outputs on the Empeg. I also have a very high end home stereo system, so anything that isn't brilliant is immediately noticeable. I did A-B tests with my CD player playing the same track...and there was definitely a noticeable difference.
All that being said...my friends all think it sounds positively great when I play the Empeg through my home system (they aren't being exposed to the A-B test) and the fact is...that even though it sounds a little dead when comparing to digital optical connection from CD player...it still sounds perfectly fine for listening and I use it all the time with no complaints.
Some day I will be able to get an MP3 player with digital outs and then all will be even better. For now, the sheer convenience of pulling my Empeg into the house and playing my playlists for parties is unbelievably cool. I can live with the sound being a tad bit "dead".