Like all HEM earphones, plugged into the right ear piece, the HEM4 really isolates. Better yet, it pretty well rejects hiss. Love everything but the AK100’s hiss? Pick your HEM. Each one I’ve spent any time with proves exactly why sensitivity for sensitivity’s sake is a dumb idea in an earphone.
The HEM4 isn’t as easy to drive as the HEM2 is. It causes my iPhone SE to lose more voltage under load, but only just. You may find that a good amp, or Apple’s Almighty 9$ Lightning to 3,5m headphone jack adapter bring out the best in the HEM4. You may also find that the HEM4 sounds perfect as-is, straight from your phone.
Prior to inserting them into my ears, I soaked in head-fi impressions intimating that the HEM4 is the lean-sounding, bass-shy, reference model in the HEM series. This is where a my ears caveat is important. While it is true that the HEM4 is cooler-sounding than both the HEM2 and HEM6, it certainly isn’t bass-shy. In fact, the z-axis space it creates in upper bass frequencies is phenomenally detailed and open. It’s just not backed by a lot of low-end sound pressure. Graded on impact, sound pressure rallies more so than the Audio Technica CK10, which, nine years on, is formidable as ever. Both err reference, but the HEM4 is decidedly more muscly.
Another thing: the HEM4’s bass is slightly warmer than the CK10’s. And again, it shows better z-axis positional detail and power. Neither are able to dredge up the extremely low opening sections to Markus Schulz’s MainStage. I’m tempted to say that the CK10’s upper bass is marginally less prone to reverb splash, but only just so. And it would be quite the boner not to mention that the bass clarity, decay speed, and attack cleanliness of both earphones are nearly unmatched by anything out there. At any price. Which is longhand for the HEM4 being up to the most speedy, layered electronic, trance, and classical snuff. You won’t find a piece of music that can stymie it.
Which brings us to mids and highs. I can’t really tell where one beings and the other ends. Mids are clear, and because they treat vocals just as they treat guitars, just as they treat percussion (which is to say, equitably) nothing jumps out at you like it does from the Meze 12 Classics. Perhaps this is the reference referenced by other HEM4 owners. Sure, the HEM4 is contrasty, with just the right emphasis on upper mids, and just the right stage extension to render complicated percussion sets and artists in holodeck reality.
Both the HEM2 and HEM6 muffle the uppermost highs. To some extent, they do the same to upper mids. The HEM6 is basically a more 3D-realistic, and bright version of the HEM2. The HEM4 is that realism extracted and concentrated into a product of its own. It isn’t sibilant. Upper mids and highs extend wide, show good depth, and almost perfectly delineate the slightest shimmer of a wind chime from the clingiest of high hats.
But you won’t buy the HEM4 if you’re expecting HEM2+HEM2=HEM4. No, you’ll buy it if for you: HEM6-HEM2=HEM4 sounds like a good idea.
Do I prefer the HEM4 to the HEM2, or the HEM6? It’s crazy, but each time I change one HEM for another, I re-discover my favourite HEM. HEM2 is my favourite. So is the HEM6. The HEM4 is different enough from those two, and, in my opinion, far better suited to trance, metal, and classical, that it is my favourite. That is, until I switch back to the HEM2. Or HEM6.
Music whose hard edges are artefacts of the recording systems of the day, definitely sound nicer through the HEM6 or HEM2. With HEM4 in my ears, I gravitate to fast, edgy, but not poorly-recorded music.
Perhaps HEM2 was too warm, too cozy for you, and perhaps the HEM6 didn’t do enough to change that impression. Perhaps you also love the CK10, and from time to time wish more earphones derived their audio engine from the ER4. If any of the above rings a bell, the HEM4 is a compelling earphone. It is a natural progression of both, and in my opinion, sounds better. It’s not made as well as the CK10, and again, its twisted cable is embarrassing. But because it isn’t nearly as strident as early ER4s, and is less prone to sibilance than the CK10, it is one of the best takes on reference out there. It is a winner.