Thanks for all of your suggestions. I checked the polarity, and I had it set up correctly. I tried switching it, and it made it worse (of course). I'll hook up the sub, too (although I was hoping that if I didn't open the box that I might get a break on the restocking fee). All of the drivers seem to be working, too. My receiver is a Yamaha RX-V2092 (ten years old, yes, but still respectable with plenty of power, and it's the one that I had hooked up to the other speakers that I mentioned which sounded significantly better).
Dave, I read Tom's review many times before my purchase, and I focused on the comments that you mention. I guess that I'm not as knowledgable as I'd like to think, but I interpreted Tom's comments to mean that the highs, while not as good as he'd like in this price range, are still quite good. If Tom had meant that these speakers had "no highs", I would find it hard to imagine that anyone would buy speakers that had "no highs". Indeed though, it does sound like the EF50s are built without tweeters. I did understand him to mean that the EF50s have no lows and would need the sub, so I expected this.
To the comment about my ears sounding clogged: I listen at very moderate, even soft volumes. My volume knob is rarely above 1/4 turn from zero.
I completely understand that different people have different listening preferences such as "hotter" verses "more laid back", or B&W vs Paradigm. To me, the difference between my previous trials and the EMPs are like the difference between DefTech Mythos ST's and a Bose Acoustic Wave Radio (I'm exaggerating, but you get my point). It's night and day.
For fun, I hooked up my 7 year old B&W DM303s that I use as surrounds in my home theater (my home theater has all B&W: these new EMPs are in my den/kitchen/family room) and placed them on cheap Walmart barstools for stands, and they sound much better than the EMPs. Next I'm going to try my 1978 Infinity Qb's and see how they compare.
Thanks for all of the help and commiseration as well. I'll keep listening and see if the sub and a short break in period helps.
I should add that I didn't go with a more full range tower because my wife has strict decor objectives. I'd love big, full range towers, but she won't go for that.