I mean, $249 is the already great price of the HE-300 and now it has this Amp with it!
This pairing should be pretty good. It looks like the EF2 amp, and I'm guessing it will sound the same and just won't have the DAC. Note - My EF2 has Raytheon 6AK5 tubes in it.
My EF2 pairs well with all of my more energetic (or even some aggressive) sounding headphones. So, not only do I like it with the HE-300 but it's pretty good with all of my Grados and especially my HF-2, plus my HD800 sound smooth and sweet with the EF2 amp. On top of that, it's still not bad with my HD600 although the HD600 don't have that last bit of detail, air, and sparkle that they get from my Woo WA6 or DACmini.
I still prefer the EF5 with the original HE-5, HE-5LE and HE-500 because the orthodynamics are more inefficient and sound best with 1-2 watts of power or more.
Not yet owning any HIFIMAN cans, I couldn't help myself and dropped the cash for the combo. It just arrived today! Never really reviewed anything so I don't think I could really describe it for you except in relation to other things, and even that probably not very eloquently or usefully, since I don't really consider myself to have Golden Ears. After only listening to it today (and thus not having enough time to get a seriously developed opinion), I will say a couple things though!
My usual setup is just from VLC on my laptop to a Schiit stack (Modi/Magni). I think the EF3 is probably less transparent than the Magni it's temporarily replacing, but is a bit darker... not necessarily a bad thing, as it seems to somewhat nicely even out my tendency to prefer brighter headphones :P The gain switch is very recessed, impossible to get at without something else (I used a pen cap.) [Er, and on that subject, should I be worried about fiddling with the gain while the amp is powered on but the cans are not plugged in, or is that probably okay?] And for the record, the "x2" setting on the gain switch is definitely plenty enough to power the HE-300, but I was just about maxing out the volume knob on that setting to get to a satisfying loudness with the 880s, so the selection is very welcome. From what I've read some people had problems with the EF-2A getting too loud too quickly on lower-impedance/higher-sensitivity earphones and not having enough volume play, so maybe HIFIMAN were listening! As for looks, although it obviously doesn't pair as nicely with the Modi, the EF3 is definitely way sexier-looking than the Magni! The bronze-on-black look is downright tasty.
And as for the HE-300, well, like I said I don't really have the experience or the hardware to tell you if it pairs particularly well with the EF3, and they've been discussed plentifully with other amps elsewhere on Head-Fi. They're a nicely detailed set of cans though, and darker to my ears than my Beyerdynamic DT-880s (I have the 250 Ohm). Better bass impact than I was expecting, for sure. I'm very interested to see how and if the sound changes as they break in, the accompanying owner's guide itself recommends about 150 hours. I already like them a lot!
...Not that I plan to stop at HIFIMAN's only non-planar offering, I mean, who could resist their higher-end models? But I can't convince myself to fork over the dough for that upgrade just yet, and in the meantime, I'll tell ya, this deal strikes me as an absurdly good one! I've seen lots of people respond to threads asking about the HE-300 by saying "If you can afford it, just go for the 400", and I've never heard the 400s before so maybe they're right, but... screw that, if you don't own anything from HIFIMAN yet and you're in the mood to acquire something new, I'd say go for the combo!