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Nexum AQUA Micro Audio Amplifier (iOS)

  1. Trager
    Great design, fun sound at a reasonable price
    Written by Trager
    Published Jul 6, 2016
    Pros - Design and packaging, fun sound signature, DAC/Amp/iPhone remote all in one
    Cons - "fun" sound

    AQUA Audio Amplifier Initial Impressions

    Many moons ago, I was at my very design-centric workspace and one of my fellow audio geeks asked if I’d seen the Kickstarter for that “tiny new audio amp.” Of course, upon seeing it, I absolutely had to try this thing. Instabuy! (Especially for the grand total of $80 US that it was going for… if it’s any improvement over the stock iPhone DAC, it’ll be worthwhile.)

    Since rumors have been flying in the meantime that the next gen iPhone might come without a headphone jack, this seems like an even better investment…if the sound is any good. While the sound signature turns out to be not exactly to my taste (I tend to like analytical and detailed), there's definitely a use for this unit. It's got a solid amplifier and a warm sound signature that will probably work for a certain segment of the listening population...especially for the modest price.



    The packaging is lovely, and it’s impressively small. 


    The included carrying case and leather storage sleeve are also nicely designed and speak to quality and design.


    My initial impression is that there’s a bit of a midbass hump, and the volume is definitely a bit higher than the stock iPhone puts out.

    Critical Listening Test

    Listening to my standard test playlist with a pair of Westone W60 IEMs:

    I Am John (Loney, Dear) – No sibilance on highs, but the climax of the song is a little congested. Definitely doesn’t sound as clean as the Oppo HA-2 that I often have used as my standard for critical mobile listening.

    Sleepless (The Decemberists) – The cello sounds really quite lovely and is more noticeable than I recall from my prior listening. I think the bass range might be a bit more extended with this amp, or at the very least, there’s more depth and presence. 

    Sleepdriving (Grand Archives) – The mids feel lush and full. I think my ears are starting to get used to the signature of this amp a little… It now feels more warm and less congested. I think I generally tend towards clinical sound, and this is definitely not that.

    Memphis Soul Stew (King Curtis) – I love this song because it has fantastic instrumental and spacial variety. As the song crescendoes, it really strains amps in terms of clarity and separation. Unfortunately, the recording is also slightly flawed (but it’s really the only version of this song). This amp certainly isn’t as spacious as others I’ve used, but it’s also not horribly congested either. I didn’t catch as much energy through the later part of the song, which makes me think there’s probably a slight treble rolloff. 

    Jumpin’ at the Woodside (Duke Ellington/Count Basie) – Talk about challenging music. Two big bands and a very conscientious mastering job. Crazy dynamics on this, plus it’s a FAST song, and there’s a ton of stuff going on because both bands are showing off every bit of their top end chops. Again, the detail might be just a little lacking (compared to the HA-2, certainly). Just to be certain of my impressions, I then listened to the same song again with just the naked iPhone (6S Plus). The mids are significantly mellower, and there’s just a bit more detail (without the AQUA).

    9 Crimes (Damien Rice) – This song sounded really good, but that’s not a big surprise. It’s a bit of a spare song, and warm/lush sound tends to work really well.

    Two Step (Bear Mountain) – ZOMG Holy Wall of Sound Batman! The forward mids and strong bass hit like a truck, especially after 9 Crimes. (Curse you, TIDAL shuffle function!)

    Artillery (Infected Mushroom) – Whoa. This sounds pretty much incredible. All of the slam and bass and wowza. That kind of electronica doesn’t really need any enhancement for detail, and the mid and bass emphasis is just about right.

    The Boxer (Jerry Douglas/Mumford & Sons/Paul Simon) – The instrumentation pushes the voices a little to the back, but that’s not necessarily a bad thing. I think the AQUA might end up relegated to when I want to really rock. Unfortunately, I don’t have my Echobox Finders with me, but I’ll be trying them later. 

    Pompeii (Bastille) – Yeah, this is pretty much what this amp is made for. Dat BASS!

    Overall Impression

    For $80, it would be hard to expect sound fidelity that’s on par with the significantly more expensive Oppo HA-2, which is the mobile amp that I have the most experience with. The AQUA is a well-designed little DAC/Amp that certainly increases audio output, with a warm and fun sound. The remote function and excellent design make it an interesting iPhone accessory… doubly so if Apple actually does remove the headphone jack from the next generation of mobile devices. 


    Putting the size into perspective…