Neurochrome HP-1

Tom Christiansen, the senior circuit designer/engineer for Neurochrome, generously sent me his premiere headphone amp for a few weeks to review. I have had an absolutely stellar time with it.

Let's start with the design. The amp is super minimalist, but I could immediately tell that every design element and feature was purposefully chosen. The gain and source switches are centered perfectly, click satisfactorily, and have no play. The XLR is recessed perfectly, and the 1/4" jack is an ease to use, as I've had amps that make it at least a little bit difficult (see: EL Stack review). The volume potentiometer actuates with purpose; it doesn't slide around or overshoot the mark. It's well indicated, and you'll know exactly where you're putting it at all times. This is really a small point, and its mentioned in the key features section of the website page for this amp, but I really like the color and intensity of the LED power indicator on the amp. Oftentimes I find modern amps to use a really harsh, small, and bright LED to indicate power, whereas this was larger, softer, and all-around more pleasant.

One of the things that I particularly loved about this amp was how easy it was to disassemble, for cleaning, gawking, or otherwise. The chassis is held together by a total of 14 screws on the outside, plus two retainers for the RCA connectors on the back. The reason for all this is of course that this amp can be ordered as DIY kit, which is a great challenge for those who are making-oriented and have at least a little experience in building amps or even just soldering components onto a board. Below is a gallery of pictures of the amp disassembled.

So now onto the sound, which actually makes this amp the stellar performer that it is. Neurochrome's website boasts "vanishingly low total harmonic distortion" figures, and they've got the numbers to match: .000017% at 200mW and 600 Ω, .000032% at 200mW and 300 Ω, and .000050% at 200mW and 32 Ω. It can push 3W per channel into a 20 Ω load at full tilt on its highest gain stage. The amp can also deliver that same power into a higher load depending on input voltage (for example, it can drive 3W into a 32 Ω load). Essentially, the output power is independent of the gain setting. That's an incredible amount of incredibly clean power. I'll be frank; coming into this review, I expected this to be a tremendously clean amp, but I didn't expect it to sound as incredible as it does. I thought this drop in THD would be noticeable, but not spectacular, and I was wrong there too. The best way I can put it, even if this is a little bit sensationalist, is that it has effectively put a veil on every other amp I've used since. This isn't to say that its turned everything that I've listened to since into trash, but there is a very noticeable and apparent difference between this and an amp with only two zeroes between the period and the first above-zero digit in its THD rating. I still have heard great, wonderful amps since, but there hasn't been anything as clean as this, if that makes sense.

My main mentality when approaching anything that gets in between my ears and the source is that it should add as-close-to-no coloration as possible. Sure, there are headphones that benefit from tube amps and the (usually) pleasant distortion that they introduce, but at my core, I'm a purist. I want the music as it is, however impossible to quantify that sounds. This is as close to that as I've ever heard. In discussion with Tom while troubleshooting some problems that lay purely on my end with the amp, he brought up that his claim to fame is that he had made as-close-to a straight wire with gain as exists. I think he's right, and I think that that is a damn good claim to fame.

As a final point, I wanted to communicate information that Tom communicated to me regarding the review unit. The unit I received was the very first build, and should be considered a prototype. Every part that affects sound and their layout is 100% identical to the production version. There is a protection circuit that lies outside the signal path which has been optimized further in the newest, production revision. The design of the text on the chassis has changed, as is visible on Neurochrome's page for this amp, and was changed from blue text on a black background to white text on a blue background. Below is a picture that deomnstrates the stock, plus two extra, colors. Those stock colors will be blue and graphite.

As a final note, here's my advice: if you share my mentality as stated above, and can afford this amp, buy it.

Disclaimers

This setup was provided to me for review by Neurochrome. I am not being paid by anyone to write this review, to endorse the product reviewed, or for the content that I put in the review.

I have had this setup for about three weeks, and I have put about 115 hours of analytical listening time through them during that period.

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Edit (4/20/17 6:38 PM EST): In post-review discussion with Tom, he alerted me that the amp can deliver its maximum of 3W per channel into any load, dependent on input voltage. This information was added in the area where its maximum output power was initially.