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Review: The HP4 Headphone Amplifier, E.A.R. of the Gods

HP4 I'm going to confess something. Ready? Headphones and headphone audio systems can be hard to like. The issue is context, for me. I come at audio's high-end by way of two-channel and multi-channel audio systems. Big speakers. Full range aspirations. Thump-your-chest bass and strain-your-incredulity dynamics. My main system can make me break out in a cold sweat, induce serious cardiac events, smite small animals and sooth even the most fevered temper. I can feel my pulse slowing, the creases from my forehead smoothing, and a general sense of peace flowing across my bones, all from just thinking about it. I love my stereo. Though, admittedly, it's kinda on the same level that the kid down the street hits when talking about his tricked-out kit car, but whatever. I love my stereo. I have not loved my headphone rig. Pretty much ever. It's not that it sucked -- it didn't. I had (and still have) great headphones from Stax, Sennheiser and Audeze with the requisite dedicated headphone amplifiers. Custom power conditioning. Custom cabling. A quality DAC. I put together all that … and I let it collect dust. It wasn't that it was bad. I wasn't. Not by a long shot. It was just … boring. By comparison. I've talked in the past about how that began to shift, sometime during RMAF this past year. It was a revelatory time, which is weird to say and weirder to go through. But it's true. Kick-a** headphones with kick-a** amplification and kick-a** digital was like an impromptu dip into the Arctic Ocean -- I woke up in a hurry. But it wasn't until the E.A.R. HP4 hit my work bench that I became a believer.

HP4

The HP4 isn’t new. It missed the 21st century in design and execution by at least a year, first arriving State-side in 2000. There’s also not a ton of info available on the unit, and aside from an all-too-short brief from Bob Levi on Positive Feedback, it doesn’t seem like Team E.A.R. has really been pushing this amp particularly hard. And that’s a shame. But given the $5,695 price tag, perhaps that’s not that surprising.

Until very recently, a price this high was pretty much unsupportable in the headphone market — and it still is raising eyebrows and more than a few incredulous rants. Sure, there were a few of the well-heeled that took such a dip, but for most of even the most financially adventurous, that kind of scratch is absurd to even contemplate in this segment, where mainstream $300 headphones is a relatively new thing.

Things have changed in the last year, with the entry of players like JPS Labs and their $5,500 Abyss AB-1266 headphones and the $4,000 Cavalli Audio Liquid Gold headphone amp, both of which I’ve had here on loan for review. But with products like these now gracing the tables at audio shows all over the US, the price of the HP4 doesn’t seem quite so improbable, even if it’s still a bit out of the ordinary.

The HP4 comes courtesy of legendary designer Tim de Paravacini, who’s E.A.R. product line has amazed not only for its performance but for its sheer aesthetic impact. In short, this stuff — the entire E.A.R. line up — is so obviously bespoke as to make even the most jaded collector sit up and say “Ooh, aah.” In a world filled with BMW and Mercedes, E.A.R. is a Rolls Royce. Top shelf, all the way.

Design and specs

From PFO‘s Bob Levi:

The HP4 uses 6SL7 valves, properly matched to the load through de Paravicini’s renowned transformers, to deliver nearly 1W of high quality, low distortion power into high or low impedance headphones. The output circuit configuration uses de Paravicini’s ‘Enhanced Triode Mode’, as employed in the highly successful V20 and 859 integrated amplifiers, while the input is also transformer coupled, giving the flexibility to accept balanced or unbalanced signals from the preamplifier.

With balanced and single-ended inputs available, it’s perhaps natural to wonder about the availability of balanced outputs, but sadly, those are not on offer. Back when it was designed, such things weren’t even dreamt of for headphones. I reached out to the factory to see what was in store for the HP4, but was told that there are no plans to update this model. On a whim, I asked if balanced outputs (one or two 4-pin XLR, for example) could be done, perhaps as a kind of one-off. I was told that while possible, this change would definitely alter the way the unit looks, perhaps profoundly, and no, they’d not done it before so there are no photos of it to give the curious a heads up. I figured it was worth the asking. Instead, we’re given a quartet of ¼” phono plug jacks, two for low-z, two for high-z headphones. Yes. Four jacks. That’s pretty much a headphone comparo-phile’s dream.

There’s an option to insert this into your mainline stereo, using the unit as a straight-up preamp, but I found that to be one of those weird why’d-they-bother additions, and didn’t play with it other than to confirm that, yes, it works. The four output jacks, however, saw a lot of use. Want to compare your Sennheiser HD800 with a pair Beyerdynamic T1? Or two sets of Audeze headphones? At the same time? Yeah. That was fun.

Here are the specs:

  • Headphone Jacks: 4
  • Features two outputs low Ƶ & Features two outputs High Ƶ (Any two simultaneously)
  • Low Ƶ output for headphones less than 40Ω
  • High Ƶ output for headphones more than 40Ω
  • Power output: 600mW
  • Frequency response  (At 1V output): (Level control @ 12 O’Clock) 20~20 KHZ, ±1DB
  • Input Impedance: 40K (Balanced or Unbalanced)
  • Output Impedance: 2Ω Low, 40Ω High
  • Sensitivity (For max output): 300mv
  • Channel Balance: ±0.5
  • Residual Noise (Volume at minimum): 90dB
  • Distortion: 0.5%
  • Button switch on front to mute throughout (Mutes Power Amplifier)
  • Power – 100v, 120v & 230v (Not rewireable)
  • Power Consumption – 25 Watt
  • Size (Excluding control knobs): W245mm (10″), D 320mm (12 ½”), H 95mm (3 ¾”)
  • Weight: 6kg (13lbs)

Sound and fury

I could make this section almost painfully short, but I’m not sure I’d be doing anyone but myself any favors. Anyway, the short form is this — at the time this hit my desk, this was the most incredible headphone amplifier I’d heard. End of line.

Specifically, well, there it’s gets a bit long winded. I think the HP4 “does something” very few other amplifiers actually do or do well — and that’s improve the performance of the headphones themselves. I mean that in the following way — most transducers (speakers, headphones) set a natural limit on what they can do. The job of the “associated gear” then is to let them do it. But given how familiar I am with my headphones, plugging them into the HP4 was very like turning the knob over into “awesome”. I didn’t get it at first. It was like the headphones were suddenly better than they were. A “12” on a 10 point scale. Nifty! Said another way, the HP4 just reset my scale.

Images became larger and more distinctly tactile. An odd thing to say about Shelby Lynne and the hackneyed cover of “Just a Little Lovin”, but there you go. The crack of the drum stick on the edge of the drum was more like a gunshot, and with the volume set just so that first time through, I flinched. Yep. That’s my, cringing into my chair. Greg Brown’s “Who Killed Cock Robin” has enough gravel in his voice as is, but here, I could tell you the what grade of gravel he was chewing and what quarry it came from. Chris Jones’ “Roadhouses and Automobiles” placed me squarely on the front stoop with an itinerant father explaining his character flaws while the summer night cooled the air, the night birds sang themselves to sleep, the crickets came out for the summer orgy, while the lightning bugs fell headlong into the zapper at the end of the porch. Okay, that last bit might have been the bourbon talking.

The main effect, and the most eerie one, was credibility. Holography, at least as it gets applied to sound staging, is the great weakness of headphones generally speaking. Honestly, it’s just hard for headphones to do imagery anywhere close to what a good stereo can do for you even under the best conditions. Headphones have their strengths. Sound stage? Not one of them. But … given that, there was something that the HP4 was able to pull off with that was actually immersive. Not saying that the HP4 “fixes” headphone-based sound stage limits, because it doesn’t. But. What it does is finally put headphones into the same ball park with a good stereo. That sounds like faint praise, but it isn’t. If you’ve been very impressed with sound stage creation, specificity, tactile immersivity of your headphone rig, then bully for you. But if that’s so, I’ll humbly submit that the HP4 is going to blow your doors off.

With Headphones

The Sennheiser HD800 is an extremely well-understood headphone (check out the thorough coverage at InnerFidelity), so I won’t bother to dig too deep here other than to note that I’ve never found a headphone (or audio transducer generally) to be as revealing as the HD800. They are, in every way, a reference-quality system and are the most detailed transducers I currently own. They are not, in any particular way, friendly or easy-going on your less-than-reference quality equipment or music. To that end, I think too many folks tend to use them as tools than as engines of pleasure — and if I was being honest, I would admit that I cannot remember the last time I reached for this pair of headphones for something other than a review.

The problem I have with them isn’t fit, which is a little loose, or the finish, which is a little silly in a Spaceman Spiff kind of way. The problem have with the HD800 is that it seems tonally balanced toward air and speed at the cost of low-end extension and impact. Its “center of gravity” is higher than, say, a pair of Audeze headphones. I’m not exactly a bass-head (though I do play one on TV), but when someone hits that subterranean note, I want to feel it. I mean, it’s in there so I want to hear it here. And that’s not exactly what the HD800 delivers. It’s got bass, don’t get me wrong. It’s just not really able to dig in; again, not like an Audeze.

It was pretty clear from the outset that the HP4 itself seemed to have a lower center of gravity, and that was good news for the HD800. In fact, it was an awesome thing for the HD800 and at the risk of burying this set of comments under a pile of hyperbole, this was the best that I’ve heard these headphones sound. Did I hear crazy-good dynamics matched with the blizzard of air and detail that’s the hallmark of this headphone? Oh yes! But my first reaction on hearing this pairing was wide-eyed appreciation for the improvement in the bass response. It was transformative. I mean, seriously. It was like the headphones were voiced on this amp and everyone not using this amp has been doing it all wrong.

Moving over to the new LCD-X headphones from Audeze, the effect was a bit less bolt-from-the-blue and a little more these-go-to-eleven. Because I kept turning the knob over and over. And no, not because I needed more volume. Because I could. No effort, no grain, no distortion, just fatigue-free escapism. Transparency was just out-of-this world, and playback with high-quality sources and music was unnerving.

The Abyss AB-1266 fared better than I expected with the HP4, but didn’t really hit what I’d call its best. Using the ¼” adapter plug for the balanced Abyss cans, I was able to appreciate many of the features I was hearing on the other cans, if to a lesser extent. While tone was limpid, dynamics were limp. I kept wanting to crank the knob — and this time, I was reaching for power. This is hardly a fault of the HP4, however — very few amps have the power to light these biker cans up fully.

Comparisons

I had a chance to sit the HP4 down next to the GSX Mark II from HeadAmp and the Cavalli Audio Liquid Gold. I’m not exactly sure how that happened, but it did. Here’s the short form:

  • HeadAmp ($3,000, review here): “blackest” backgrounds, with deepest apparent reach to the bass. Very linear.
  • Cavalli ($4,000, review coming): widest/tallest sound stage, with best specificity of placement. Warm, non-fatiguing, extraordinary sense of power.
  • E.A.R.: Best tone/timbre, imaging. Stereotypical tube benefits to soundstage. Some softening of bass impact in comparison to others. Least apparent power.

These three amps are the very best I’ve ever heard in the headphone amplification department. Any one is a keeper and I fully consider all three to be “enders” when it comes to The Search For Audio Joy. If any one of them ever finds a home on my audio desk, I’ll be thrilled.

Conclusion

EditorsChoiceSmallThere are a few of my friends over at Audio360.org that believe that the HP4 headphone amplifier from E.A.R. represents the pinnacle of headphone amplification — both in design and in execution. It really is hard to disagree. Stylistically, it is by far the most elegant (and compact!) of the flagship headphone amps I’ve had access to, and having it grace my desk even for 5 minutes (much less a couple of months on loan) was enough to make me grin in an unhinged kind of way.

The HP4 made me want to touch it, to turn it on, to plug in and get lost. That’s about as much as you can ask for from any component, but the fact that this one actually can take you somewhere else shoots this amp to the very top of the design charts.

In short, I’ve heard amps that can do a lot of wonderful things. But I’ve never heard an amp that was clearly better than this offering from E.A.R. Different? Sure. But better? No. And none of those made me want to empty my wallet quiet as thoroughly as this one. It’s a work of art.

For more information, check out E.A.R.-Yoshino and the USA distributor, Dan Meinwald of E.A.R. USA.

HP4

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About Scot Hull (979 Articles)

Founder, Editor and Publisher at Part-Time Audiophile and The Occasional Magazine.

3 Comments on Review: The HP4 Headphone Amplifier, E.A.R. of the Gods

  1. HP4 is terrific headphone amp and beat Decware and Alo….very easy on the ears but after I heard Apex Teton with HD800, the realism was too addicting and had to switch.

  2. Told you! 😀 Love the review BTW, captured so much of what we feel when we listen to the HP4.

  3. Gavin Hadley // September 26, 2014 at 11:36 AM //

    Scot old buddy I’d like to see a review of the Cary Audio HH-1 Hybrid Tube/Solid State Headphone Amp. I own one and paired with my old Sennheiser HD600s find it pretty hard to beat given its price. Check it out!

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