Hmm.. Well this is interesting.. I do have to go on record, you can call me nuts, but if in anyway the Zu's with a total of 12, 10" drivers cannot reproduce the explosive transients of a classical recording with ease, over a sytem with a total of 2, 6.5" drivers than there are serious problems here. Anyhow, fact is the Definition's soundstage suffers due to the super stiff drivers for the first 300 hours.. Okay maybe 200 hours. This is the only reason anyone would think they don't grasp the sound or something is funny in the begining. They sound a bit compressed and disconnected, virtually like if you were to hook a standard dynamic drive speaker like the merlin up out of phase on accident. There is nothing to get use to in the Zu's sound, they do no miracles they sound just like any speaker and mostly better once they open up and are matched correctly to the right front end.
Beyond that I agree with the above that you could not pick a more different design, but not necessarily a more different sounding speaker.. Only thing they have in common is the price point. Which one represents better value and realistic sound? Well that will be up to you to get a hold of a pair of each. You say that you have heard the merlins lower tier, well my suggestion is take advantage of Zu's 90 day trial, cause you are spending a lot of money, and if you feel they are a step in the right direction over what you remember in the merlins, than make a decision based on your likes and dislikes.. Bottom line they will not totally open up without a good 2 weeks of at least 8 hours a day of music signal. Just run them at a normal level while your out to work or something, this is the only advise I can give.
Beyond that I agree with the above that you could not pick a more different design, but not necessarily a more different sounding speaker.. Only thing they have in common is the price point. Which one represents better value and realistic sound? Well that will be up to you to get a hold of a pair of each. You say that you have heard the merlins lower tier, well my suggestion is take advantage of Zu's 90 day trial, cause you are spending a lot of money, and if you feel they are a step in the right direction over what you remember in the merlins, than make a decision based on your likes and dislikes.. Bottom line they will not totally open up without a good 2 weeks of at least 8 hours a day of music signal. Just run them at a normal level while your out to work or something, this is the only advise I can give.