I haven't got a horse in this race as I'm not an E3 owner but I do think that two songs is not enough to be able to give an opinion either way. Perhaps your expectations were too high given the hype that the E3 has generated especially with your current headphones in your signature being all dynamic drivers. Dynamic drivers can be more exciting, especially with closed backs because of the constraints and tuning of individual models. I've also found that planars and something of a different beast than dynamics.
We all, more likely than not, have favourite tracks that we use for auditions. Some will show up the strengths of a particular model of headphone others may surprise you with a lack of what your looking for in that model. That's why, to me, it's important to vary your music when auditioning. I certainly have whole albums that I prefer listening to on either the planars or dynamics.
If you can get a home loan with the E3s then that is going to give you a true impression of them one way or the other. I've rejected two pair of headphones in the last few months, one of which had glowing reviews in the press yet I didn't like one of them one little bit and that was the Focal Radiance. Expectations with headphones, or any bit of kit to be honest, can work against you on a very quick audition because the grey matter needs to have time to adjust to the new sound.
As for power everyone will have a favourite amp, some will give good synergy some will not but again that personal. I'm using a Lehmann Linear, a design which is decades old. It's power and neutrality has never failed to power anything I've thrown at it.
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