hippo box+ headphone amp in review – petty in pink

Just slightly bigger than iBasso’s fabulous T3, hippo audio’s second self-branded portable headphone amp is a diminutive, but well-punctuated statement product. iBasso’s effects-be-damned neutral sound is damned in return as the box+ sways the portable audiophile with ‘rich’ sound, the sort made possible only through a Butterworth low pass filter: the sort of sound that has made Head-Direct’s Hifiman series famous.

I’m sorry, but I don’t have a box or any marketing literature, so I can’t write down manufacturer’s specs (which often don’t pan out anyway, so I’m not bothered too much).

Build Quality
Thanks to its solid aluminium chassis to its all-metal phone jacks, the Hippo+ looks and feels like a million dollars. Its tight frame is fastened by countersunk Phillips screws and military edges. This thing will outlast your iPod.

Unfortunately, that’s not the whole story? The hippo box, its predecessor, succinctly split amp functions between bum and face. Power and sound functions shared one side, while LED, in and out, shared the other. The hippo box+ bungs that up. Now, the in and out ports feed from opposite sides and the bass and gain functions are broken away from the USB jack. Splitting the ports between sides puts greater stress on line and earphone jacks, raising the possibility of cable breakage, not to mention ugly ergonomics.

Ergonomics and Polish
Don’t worry audiophiles: this amp performs well. You’ll be happy with its lushnessness and smoothicity. As a music-loving users, however, I am bummed by its design. The hippo box sucks to use and here’s why: it is bass-ackwards. As mentioned above, the In and Out ports are split up. If you like to use an amp with your iPhone, you’ll have to turn it ass-up, or find a long interconnect cable and raise the possibility of bending your headphone jack in the process. Players with headphone jacks positioned on top fair much better. And, since the amp is a perfectly symmetrical brick, blind operation, especially now that the headphone ports are split, is touchier and feelier than ever before.

The next WTF point is the audio function sliders themselves. Both work as advertised, bass gain beefing the signal by up to 5 decibels, and a decent ~5 dB raise in overall volume gain. Great. The problem is that neither bass nor gain is labelled. Which way is on? Which way is off? Every unit I’ve played with is lost. The low gain position is on the right and hi gain is on the left. Okay, so the bass function is probably the same, right? Nope. Bass goes the other way: OFF is left, ON is right.

Again, be careful not to bend your earphone jacks, which thanks to the split front-back in and out ports, is so easy to do. When both ports are on the front OR the back, it is easy to keep track of cable pressure. Wouldn’t it suck to buy a cute little amp only to find that after a little careless use, your favourite earphone’s cable broke? Smaller and lighter amps like the GoVibe Single, and Houdini Xin Supermicro, and the Pico Slim are examples of amps that work in this configuration because their body size isn’t as clumsy, and because they have volume pots.

The lack of volume pot on this amp is its main detractor. To change volumes, you have to adjust the sound level at the source, just like the Firestone Fireye I. But, unlike the Fireye I, the input and output jacks are on the opposite sides.

It’s not just ergonomics, though. Lack of volume pot spells certain sound nastiness for players with high amounts of noise in their signal.

The final insult to the hippo box+ skin deep: the website, www.hippoaudio.com, which is printed in bold, contrasty font, is a dead link. I’ve checked and rechecked. IE – dead; Safari – dead; Chrome – dead; Firefox – dead. It’s not a browser or web standards issue, it’s simply that the website doesn’t exist. I know that it is hippo’s second amp, and that the company is still new to the area, but the competition from Fiio, iBasso, and Firestone, just don’t make the same mistakes.

Up till now, I’ve offloaded a lot of negative stuff about the hippo box+. But that stops here – for the most part. As long as you can get past its clumsy interface, dead website, and shocking lack of a volume pot, you have a pretty decent headphone amp. It doesn’t so much amplify the signal; rather, it adds a meagre several decibels to the signal when the high gain position is selected. In other words, you won’t be using this to boost your power-hungry Beyerdynamic or Sennheiser headphones – much. The bass boost drops the signal volume by about a decibel, but raises the low frequencies up to a healthy five decibels. In low gain mode, the gain is more modest.

Both are clean and work as advertised – as long as you don’t expect earthquakes from your ears. If you want that, look no further than Graham Slee’s Voyager.

The battery seems to last a good while, but to be honest, I’ve not even tried to run it out – I simply need my iPod touch and can’t be bothered to hook earphones and cable up to it till the box+ runs out of juice. I’ve set it to run all night hooked up to my work craptop and come back in the morning to a still-healthy box+. Charging is a breeze thanks to the mini-USB connection that can be found anywhere and finishes up in just a couple of hours. It’s quick and painless.

Sound Quality
Here is where the hippo box+ recovers most of its losses. It isn’t an all out performer, but I don’t think that was hippo’s aim. All-out performers have no sound. They aim at neutralising the deleterious effects the poorly-implemented headphone outputs of some audio sources. They correct roll-off, lower distortion, and keep signal noise to a minimum. The hippo box+ does keep a well-tailored signal. It has no problem driving low ohm earphones, and when set to hi-gain mode, sustains great stereo image. But hippo graced (and I say this for the audiophiles out there) the box+ with a Butterworth high-frequency roll-off.

It’s not a load-induced problem. It exists in unloaded signals, too. It’s simply the sound that hippo want from the box+. Low pass filters are almost always immediately recognisable. My Hifiman and Teclast T51 have similar filters that I picked up on immediately through my great Westone 4 earphones. Performing hardware tests only confirmed my suspicions.

I like low-pass filters, and actually, use EQ apps like Equalizer and EQu to imitate with certain earphones and albums. There is nothing wrong with a low-pass filter – that is unless you want neutrality. Low pass filters are great if enjoy a smartly dulled high end.

The advantage of an outboard Butterworth is that you can enjoy it on any device. So, my bright iPod touch and HiSound AMP3 Pro smooth out pleasantly in the top end. Apple have never included a hardware EQ chip in the iPod/iPhone line. Using apps like EQu gets you great, tailored sound, but at the expense of battery life and some distortion of the signal. The hippo box+ does the grunt work for you – that is if you like it dark and strong.

The bass boost adds ample kick at the bottom. It isn’t as smoothly set as the FiQuest, but at 3-5 decibels, it is just enough to nicely complement the low-pass filter. It never distorts and retains a good, clean signal down to its lowest audible bounds.

The difference between high and low gain are pretty stark. Low gain is like training wheels. It feels safe, but in box+’s case, it is instable. High gain gives a cleaner, louder, more precise signal to your favourite earphones, bass boost enabled or not. Don’t ask me why. Since the volume difference between the two settings is very small anyway, I wonder why low gain even exists in this amp.

My final technical observation is another tick against the box+. Its noise floor is pretty low with moderate to low levels of hiss, but since there is no volume pot, you cannot control the noise of your source. Modern iPods are perfectly safe at any volume. They just don’t hiss. But other great players, like the Sony Walkman series, or wannabe’s like HiSound’s AMP3 Pro, Studio, and Rocco, force the hippo box+’s worst hand. When fed dirty, noisy signal, the box+ spits it out the way it came. There is no way to take advantage of the amp’s cleanly output without ruining your ears. If you listen to your AMP3 Pro 2 or iPod touch at 50% volume, you will listen to them plugged into the box+ at the same volume. The iPod will sound fine, but the AMP3 Pro 2, a player I always pair with an external amp, will hiss and howl. Noisy sources need signal attenuation. They should be set to spit out optimal signals and then attenuated by an external amp. Not possible with the box+.

Now, for the audiophiles: the box+ sounds dreamy. The flip of the bass and gain switches gives you the best results for: volume, signal quality, stereo image, and distortion. The hippo box+ also has a punchy dynamic range. Like the Hifiman, it plays the upper frequencies softly so you can relax with your music.

While I appreciate the Robin-Hood accuracy of the ALO Rx headphone amp, this warmer, milder box+ sound, is great. If you’d like it even cosier, flip the gain switch back down and enjoy less stereo separation and more coherence. Overall, this little amp does its audiophile job very well as long as it is plugged into the sort of audiophile that likes warm, relaxing signals.

Again, if you enjoy the Hifiman and Teclast T51, the box+ will put you there, but for a much, much milder price. And, if you pair it with your iPod or iPhone, you won’t have to sacrifice on the goodies that Apple have brought to the masses: gapless playback, low levels of hiss, good ID3tag support, album artwork, and much much more.

It’s hard to really recommend the hippo box+ unless you already have a great portable setup, or you are a casual listener. It is a good-sounding, if quirky amp. It maintains a Butterworth tailored frequency response that will pull at the heart-strings of emotional audiophiles and people that have trouble with sibilance.

For me, however, the reason this amp scores no better than a cautious TAP is that for its cost, the hippo box+ will cause you to scratch your head in wonder. What in hell were hippo thinking when they printed the absent website, www.hippoaudio.com, across their newest amp? How did they forget to label the bass and gain settings, especially as both actuate in different directions? For a 99$ market price, this is a bust. Even at Jaben.net’s 68$ price point, it is a hard to recommend against the competition from Fiio and Firestone.

Again and again, audiophiles prove why regular Johans need to be brought into the development phase.

Dear Hippo box+,

I really really want to recommend you: I believe in your cosy sound, and your wonderful size and build quality. But you’re bound by myriad developer blunders and oversights that besmirch your good intentions and optimistic MSRP.




  • Great build quality
  • Diminutive size
  • Soft, cosy sound
  • Conservative, but resolved bass settings


  • Ergonomawhuts?
  • www.hippoaudio.com?
  • Bass and gain settings not labelled
  • No volume pot
  • Little actual signal amping

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