Review: The Z:ero digital earphones from Zorloo

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The Z:ero earphones deliver clear and detailed audio, though they're not exactly plug and play(Credit: Paul Ridden/Gizmag)

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Hong Kong-based Zorloo headed to Indiegogo earlier this year to crowdfund some next generation earphones that integrated a digital-to-analog converter (DAC) and headphone amp into the inline controller. By the time the campaign closed on February 22, the campaign had attracted over US$85,000, nearly four times the funding goal. Now, after a slight production delay, backers are starting to receive their Z:ero in-ear headphones and the company's Andy Ho sent Gizmag some to try out.

Rather than route an audio signal through an audio jack and then on up to the drivers, Zorloo's earphones are plugged into the micro-USB port of an USB OTG-capable smartphone or tablet. This effectively diverts the audio signal from its normal path, bypassing the smart device's own amp and running it through the Z:ero inline control unit. At the heart of this 5.5 cm (2.17 in) long box is a six layer PCB sporting a Cortex-M3 processor and a Wolfson WM8918 DAC and headphone amp.

This is said to produce up to three times the output power of a regular smartphone's audio jack, meaning that the audio processing strain is taken away from the music player. Meanwhile, the volume level of the music player running on the source device can be turned down and the user can still listen at a comfortable level but should be treated to higher quality sounds.

The Z:ero earphones are reported capable of supporting audio formats up to 16-bit/48 kHz resolution over a frequency range of 20 Hz to 20 kHz, with 96 dB SNR, a total harmonic distortion of 0.02 percent and 32 ohm impedance. The max output power is given as 27 mW.

Not exactly plug and play

For the Android source device to work with the Z:ero earphones out of the box, it needs to be able to act as a USB host and have support for USB audio. There's a (quite short) known device compatibility list on the company's FAQ page, and Android 5.0 Lollipop boasts USB audio out support. Some manufacturers may have included USB audio with Android 4 (and earlier) smart devices, but the odds are that most potential users will have to put in some thought and do some homework before jumping into the Z:ero pond.

"The problem of compatibility is mainly with the USB OTG and Audio support at the host platform and there is not much we can do," admitted Ho. "Lollipop will likely solve this issue. In the meantime, we are discussing with a third party music player developer (with included USB audio driver) to see if we can bundle the app together."

Zorloo recommends that anyone who owns a USB OTG source device not already compatible with USB audio gives the third party app USB Audio Player Pro a whirl, which includes its own USB Audio driver. Though there is a free trial available, the app proper is not free and adds more cost and more complication to the setup and use process. It will also only allow the Z:ero in-ear headphones to be used for digital music listening, and only within the app itself (the USB Audio driver isn't shared with other software).

There are a few other mobile music player apps with USB audio, and even one or two no cost alternatives kicking around (such as the Hiby Music Player), but we feel that the recommended app is worth the outlay.

Another thing to consider is exactly what kind of digital entertainment you enjoy when out and about. If it's restriced to music/audio, then a USB OTG Android device, the Z:eros and Lollipop or a USB audio-packing app should see you right. But what about watching videos? Ho told us that he has not yet found a video player with a USB audio driver built in, so unless you're using a laptop or can get a helping hand from Lollipop, for the moment at least, watching (and listening to) online or stored videos using these earphones is going to be troublesome to say the least.

By now, you may be wondering when we were going to get around to support for iOS. Well, there isn't a dedicated Apple-friendly version of the Z:ero in-ear headphones at present, though some cable wizardry involving the Apple Camera Adapter and a USB type A to micro-USB Type B adapter could result in some success (not tested as part of this review). Zorloo is planning to embark on another crowdfunding effort to bring a Lightning Z:ero into being though. As for Windows Phone users, you can pretty much forget about it.

If you have a micro-USB Type B female to USB Type A male adapter, the Z:ero in-ear headphones can be used on modern Windows/OS X/Linux machines provided USB audio is selected as the audio output device.

Z:ero or hero?

For the most part, I've been very sensible and kept overall volume levels at a comfortably immersive level. For the purposes of being thorough however, I did liven things up to Motorhead concert levels (well, not quite) and found that when the volume on the Z:eros is turned up to the max there's an audible background hiss, which is only noticeable on quieter acoustic tracks like Eric Johnson's wonderful Ciel.

Since running both the source device and the earphones at full volume is, quite frankly, painfully loud and not recommended, the hiss can be dispensed with by turning down the device volume and adjusting the Z:ero amp's volume to taste. Volume up and down buttons don't respond to press and hold commands, but prefer a tap action to increase or reduce the sound level.

With the source player returned to about 20 percent volume and the inline DAC about three presses up from default, I found the the acoustic picking in Ciel to be very clear, clean, lively and natural, though the sound signature did seem to nudge a little toward the lower registers. I was expecting to be forced to listen to cold digital precision, but the Z:eros offered a surprisingly warm reproduction.

"We target the young generation on pop/electronics music so most tuning has emphasis at the mid to low frequency band," Ho told us. "There is also a limitation due to the neodymium earphone drivers used. In our next generation product, we will use a dual-driver earphone and this should provide a better response coverage."

I reckon that this might be a good time to mention that, for the most part, the music I've been listening to with the Z:eros plugged into my ears have been MP3s. I have ventured into FLAC territory from time to time though, but only when connected to my laptop using the micro-USB to full-sized USB adapter that Zorloo kindly supplied me with (this isn't normally part of the Z:ero package). I was going to pop a few high resolution WAV files onto my laptop playlist, but Ho explained that if I was to try and play a 24-bit/192 kHz audio file, Android would down convert the resolution to match the maximum supported by the earphones – 16-bit/48 kHz.

On the subject of FLAC, Money by Pink Floyd is generally my go-to digital music file when trying out new audio equipment. Direct output from my laptop's audio jack has proven to be rather disappointing, but the Z:eros punched well above their price range peers and treated me to a spacious rendition with good, well-placed instrumentation throughout. The reproduction was clean and detailed, though there was an audible crunch when the center button of the controller was used to stop, skip or restart tracks. And there was also a slight delay between pushing the button and the appropriate action firing on the source music device.

Though my Z:ero listening hours have featured a broad range of music from various genres, it's often the quiet moments that stand out when reviewing earphones. Just one guitar and one voice can separate the great from the good or the shiners from the disappointing. The combination of the powerful USB Audio Player Pro app (flat EQ) and Zorloo's Z:eros managed to add some quality spice and memorable warmth to a regrettably lossy MP3 version of Pride by Kash Lewis.

Likewise for the gritty Mr Highway Man by The Damned and the Dirty playing on my tablet, where the Z:eros delivered a nicely separated railway rhythm, added some lively snap to the acoustic slide guitar and allowed the throaty vocals to cut through nice and clear.

The Z:ero earphones and the integrated electronics all draw the power they need from the device they're connected to, which Ho reckons to be "around 50 mA." I found that my Galaxy Note 8.0's generally impressive battery needed me to whip out the charger a little more often, with a very unscientifically measured overall dip of about a fifth on what I'd normally expect to get out of it.

The 130 cm (51 in) bi-colored shielded cable is a good length for music on the go, though since many Android devices have their micro-USB port on the bottom edge, the cable can seem shorter than it actually is.

For Reasons to be Cheerful, Part 3 by the late, great Ian Dury, I opted to try a CD via my laptop's optical drive. Again, the Z:eros delivered some good stereo imaging and instrumentation throughout this novel, upbeat ditty and provided plenty of room for Dury and the Blockheads to impress, particularly in the percussion department.

With Clouds on the horizon, an entertaining guitar duel from Walter Trout and Joe Bonammassa, the constant one-upmanship riffing of the two main players can make it easy to ignore the solid performance of the other musicians present. Indeed, the chugging bass and inventive percussion can seem somewhat drowned out through earphones where spacing is an issue, but I certainly didn't find this to be the case with the Z:eros.

Ending the usage section on a slightly sour note, the Z:eros come with small, medium and large silicone buds, but even with the one most suited to the size of my canal fitted, these earphones were not what I'd call comfortable and I had problems persuading them to stay put when on the move. As such, passive isolation at normal listening levels wasn't particularly effective on busy commutes, which made the volume up button on the inline controller far too tempting a proposition.

The bottom line

Though I regularly use a digital-to-analog converter/headphone amp to pummel digital music output into something resembling high quality when plugged into my laptop, carrying one around with my dedicated digital music player, smartphone or tablet is often more trouble than it's worth. That Zorloo has managed to squeeze a DAC/HA into an inline playback/volume control unit of a pair of earphones makes the Z:eros an attractive proposition.

The cherry on the pie top here is the promise of an improved listening experience, and the Z:eros consistently delivered. Clean, clear and detailed, with unexpected warmth. The build quality is good and the semi-hard fabric case the Z:eros are shipped in has bags of room inside. It's not all plain sailing though.

When Android 5.0 Lollipop is but a distant memory and all Android devices have USB audio beating at their hearts, the need for potential buyers to do some homework before jumping over the Z:ero fence likely won't exist. For the moment though, Z:ero use takes some prior consideration.

That said, if your source device does tick all of the compatibility boxes, on its own or with some third party app help, we'd heartily recommend giving Zorloo's creation a whirl.

The Z:ero digital earphones will be available in the consumer space shortly in black/red or black/gold for $39.

Source: Zorloo

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