I did. I did some extensive listening last night with the HE-4 and that puppy can definitely power them, but so can the Ember. In fact, the Ember is a better amp all around, but not by a long shot. Emotiva is slightly thicker and slightly more congested. Ember has just as much speed and punch, but it sounds airier and separates instruments so flawlessly.
For example, if you listen to Heavyweight by Infected Mushroom, about halfway through the song there is a section where the intensity drops right before going into a high energy rhythm guitar with a wicked guitar solo on top. Now, if you listen very closely to the rhythm guitar, there is a very quiet yet sharp electronic synth that "sparks" alongside the guitar. With most of my dynamic headphones, you have to try really hard to hear it, with planars it's much easier. With the HE-4, even easier. With the Ember + HE-4, you couldn't miss it.
I would say that after my session last night, the Emotiva is about 90% as good as Ember (at Ember's lowest output impedance setting). Yes the Emotiva is a lot cheaper, but Ember has the ability to switch out tubes, adjust output impedance, and adjust gain. I haven't ever needed to increase the gain on Ember, if that puts it into perspective.
This brings up the power debate again (oh no!) but I found a table, thanks to a user at another headphone forum, which helps describe the amount of power "required" for each headphone. I'm going to just copy a tiny bit of info from it for the three headphones mentioned in this thread:
|Power Rating||Efficiency||90dB SPL||105dB SPL||120dB SPL|
I didn't include voltages because I don't think it's necessary to show that even though Ember doesn't put out as much power as many of the amps out there, it puts out enough to get to 110dB, which I will kindly stay away from, haha.