Review: Miyo DAC/amp turns up the heat on handy hi-res music listeningView gallery - 12 images
Just over a year ago, a bunch of audio nerds launched a Kickstarter to get a new digital-to-analog converter and headphone amp into the hands of fellow high resolution music lovers. The Colorado startup promised backers that the palm-friendly Miyo would deliver the same kind of audio quality and sonic detail found in a professional recording studio. The campaign proved successful and the aluminum brick has since started shipping to consumers. We've spent the last few weeks rocking out with this useful audio toolbox, while also feeling the warmth radiating from the device itself.
Our Miyo review unit came in a simple black card box that also contained a short USB A to micro-USB cable and an invitation to visit the support section of the product website – and that was it. There was no user guide or manual showing the ins and outs, or revealing the mysteries behind the 12 LEDs to the top of the textured aluminum housing. Of course, the chances are that you wouldn't have the device in your hands unless you knew at least a little of what it's supposed to do, but the lack of offline pointers did strike us as a little odd.
The information blanks can be quickly filled in with a visit to the product website, particularly the support and smarter design pages. The Miyo is powered over USB, either via the Windows, OS X or Linux laptop or computer that's feeding in the music or using a mains adapter. The DAC/amp can be used with mobile devices, but only while the Miyo is drawing the power it needs to run from a separate power supply or external battery pack. A smartphone or tablet just won't cut the mustard on its own.
"Mobile devices are not able to supply enough power to Miyo via USB, so you have to use a powered USB hub, power bank, or a Y cable that let's you get power from your device's power supply (ie. iPhone charger, etc)," the company's Jon Hillman told Head-Fi community members during the Kickstarter campaign. "So while it will work, we don't think it's an elegant solution for listening/recording with a smartphone or tablet."
The supplied 8.75 in (22 cm) USB cable sports nifty a double-sided USB A connector, so there's no wrong way to plug it in. We did experience a few problems with the supplied cable (we used a Samsung Windows 7 laptop and a Macbook Pro for our digital music sources for this review). On a few occasions, the Miyo didn't fire up on first plug in, so we had to remove and replug. We didn't have such problems when using a standard USB A to Micro-USB cable.
"Honestly, we were a little disappointed with the cable we sourced (after verifying samples, of course), and are sourcing new ones to replace it," Hillman told Gizmag. "We intentionally used the most readily available USB cable (thanks to the Android phone market), figuring that given our design the only long term potential failure would be the cable itself."
Though up to date Mac and Linux users should be able to enjoy plug and play operation out of the box, it's a little more complicated for Windows users. The Miyo will work with Windows machines without any action from the user, but for some odd reason known only to the folks in Redmond, Windows does not support USB Audio Class 2.
This essentially means that if you're wanting to take advantage of the Miyo's 24-bit/192 kHz high resolution music playback prowess (by way of comparison, CD audio resolution usually has a 16-bit depth and 44.1 kHz sampling frequency), you'll need to download and install the free driver from the Support section of the Miyo website.
A quick look under the hood
Digital-to-analog conversion is undertaken by a PCM1792A DAC from Texas Instruments, while a PCM4220 takes care of analog-to-digital conversion. The Miyo also packs low jitter (500 femtoseconds) MEMS-based audio clocks, OPA1664 and THS4532 opamps and TPA6120 headphone amps. The isolated headphone amps are reported powerful enough to drive even the most demanding high-end headphones, with maximum output quoted as 25 mW into 600 ohms.
With the Crossfade M-100s used for the majority of this review, the max output is given as 200 mW, and we can confirm that the Miyo gave a significant boost to the volume coming from the laptops it was plugged into. We'd heartily recommend setting the source volume at zero and then gradually pumping it up to avoid painful surprises.
The circuitry is wrapped in a slick-looking anodized aluminum block with beveled edging and 12 spots that allow multi-colored LED lights to shine through. The housing doesn't just look good, it also acts as a heat sink. As such, it gets quite hot very quickly – not just warm to the touch but actually hot. While this is not enough to burn, caution is advised when handling the Miyo after playback. We asked Hillman if running hot could lead to premature unit failure.
"Based on our studies and testing, we expect no long term issues due to heat," he told us. "To that extent, we've tested in fairly extreme conditions (over 160° F/71° C) to find the limits, and in that case there is thermal protection in several key areas that are built into our ICs (the power supply being one of them), so that MIYO will simply shut down if it overheats. The PCB manufacture, layout, trace widths, solder, and finish were all selected with long term performance in mind."
Should Miyo users encounter any issues with the DAC, the company offers a lifetime warranty for peace of mind.
The Miyo has two 3.5 headphone jacks, meaning tunes can be shared with a friend or colleague without having to remove your own headphones. Both jacks share a single DAC, but there's no loss of volume when a second pair of cans are plugged in, and no crackle or clunk noise as the 3.5 mm plug is pushed into the other jack. The headphone jacks also glow red, indicating that an optical (S/PDIF) cable can be connected (for digital audio output at up to 24-bit/96 kHz).
On the opposite side to the twin headphone jacks is a 3.5 mm line-level input with RFI filtering and static shock/overvoltage protection. This allows for the connection of mobile music players, such as smartphones and tablets, to amplify the analog source. The Miyo will need to be connected to a mains supply in this mode.
There are no hardware volume controls on the Miyo, its DAC attenuator makes use of operating system volume controls, ensuring no loss in audio quality as levels are reduced.
In playback mode the LED light meters display the pre-attenuation stereo audio levels that Miyo's DAC is receiving from the source. From the USB plug end, blue lights come on in six steps for left and right outputs. If the output increases beyond the -18 dBFS max range, the lower lights illuminate white in 3 dB increments. If clipping occurs, the top LEDs turn red.
When an audio cable is plugged into the input port, say from digital music creation hardware, the meters automatically change to offer useful visual level guides for recording, such as dynamic range and input clipping. The LEDs closest to the input jack show input levels, while those nearest the output jacks show output levels. Left and right input/output indicators are split down the middle, and indicators move out from the center, so the Miyo is probably best viewed with the USB port to the right. The output level indicators are as before, but the input run green then yellow, with red indicating that nasty clipping.
Powering on and feeling the heat
When the Miyo powers on, the LEDs run through a colorful startup sequence and then pulse to the right, and then to the left, until source audio is detected. As mentioned earlier, this mini desktop DAC/amp can provide a significant volume boost to all but high-end headphones, so setting the operating system's output at off or very low is advised. Within a couple or three minutes, the aluminum housing is warm to the touch and soon runs hot, so also have the oven gloves on stand-by.
Though the Miyo didn't appear to punish lossy MP3s and AAC files too harshly, the lack of sonic detail in such formats soon became evident in reference tracks like Pink Floyd's Money and Cathedral in a suitcase from Pat Metheny, though a tight response and confident delivery lifted the game somewhat on pounding head-boppers such as Firebirds by Clutch and Disturbed's Immortalized. Having to find a wall outlet or external battery pack to power the device when mobile, though, did kind of put the dampers on our portable pleasure.
The listening experience improved considerably when higher resolution FLAC and WAV files were played through the free Foobar2000 audio player (Windows). We immediately detected a widening of the stereo image and spacing aplently for the trio of beautifully-played guitars, soothing bass and subtle percussion on the 24-bit/192 kHz resolution FLAC version of Old Man from ZZ Top's First Album, for example, bringing an "in the studio" feel to the reflective lament.
"The imaging you hear is likely the result of the clocking (extremely low jitter – the use of MEMS-based oscillators for clocking is a first in audio design) and slew rate of the headphone amplifier 1300V/µs (very tight transient response, so the whole soundstage opens up)," said Hillman. "Both of these are critical to achieve excellent left-to-right placement and temporal resolution with respect to transients (less 'smearing'). There is no DSP or other processing specific to imaging (or anything else) being done. Extremely low noise helps in this regard as well, where lower-level sounds are resolved more easily within the overall mix, which results in a more '3D' or 'front-to-back' kind of sound."
The Miyo also facilitated a cramp-free experience for the busy title track of John Coltrane's Blue Train in 24-bit/192 kHz WAV format, which proved lush and entertaining with plenty of room for each virtuoso performance to breathe. The DAC/amp managed to capture the vitality and enthusiasm of tracks like Ain't nothing wrong with that by Robert Randolph and the Family Band and Rattlin Bone's Shoot Me Down as they rushed through on their way to the headphones, with the output direct from the internal audio circuits of our aging Samsung workhorse and the newer, fresher Macbook Pro sounding thin, lifeless and insincere by comparison.
The mini DAC/amp proved itself capable of picking out intricacies and nuances sometimes missed by more expensive and bulkier desktop devices, and effectively communicating those facets to the listener. It managed to keep a tight grip on sonically rich tracks like Cathedral in a suitcase by Pat Metheny or full orchestral delights such as Tchaikovsky's Symphony No. 5 in E minor, Op. 64, and brought natural, engaging and intimate vinyl-like warmth to Up & Rise by Hazmat Modine – despite a slight drop in resolution to 24-bit/48 kHz FLAC.
When used as part of a recording or mixing workflow, with music creation hardware plugged into the line-level input jack and recording or mixing undertaken via USB on a computer or laptop, we found the input/output metering both intuitive and informative, helping to capture clean and detailed digital audio with ease. The LEDs illuminate with variable intensity, allowing for more precise control of the levels. We also found it useful to be able to plug in a second pair of monitoring headphones and allow a colleague to help fine tune the mix, or feed the output to a pair of powered speakers to share the tunes with everyone.
The bottom line
Compact USB DAC/headphone amps like Cambridge Audio's DacMagic XS or the ZuperDAC from Zorloo are designed for portability, and generally powered by the source music device they're plugged into. Desktop varieties are usually a good deal bigger, ranging from pocket-friendly units such as RHA's upcoming DACAMP M1 to bulky beasts like the Yggy from Schiit Audio. They almost definitely require their own power source, are capable of driving even the most demanding of high-end audiophile cans, offer more in and out options, including Toslink, AES/EBU and RCA, may support the full range of high resolution formats, including DSD, and could even include some wireless streaming functionality.
The Miyo sits somewhere in the middle. Its 2.8 x 1.5 x 0.75 in (72 x 39 x 19 mm) dimensions and 6 oz (170 g) weight certainly makes it pocket-friendly, but the fact that it draws power from the Windows/OS X computer or laptop it's connected to over USB, or from the wall outlet via an adapter, makes it less mobile-friendly. On the plus side, it's capable of driving cans with a 600 ohm impedance, has a line-level input and two headphone output jacks and supports high resolution PCM-based audio playback out of the box.
Compared to the rather unsatisfying, closed-in sound from 3.5 mm audio jacks of the Windows 7 Samsung notebook and the Macbook Pro used during the review, the Miyo offered up a much improved listening experience for computer-fed music, movies and games.
Though we pretty much stuck with the Crossfade M-100s for much of the review, we also popped a pair of cheap Beyerdynamic headphones over our ears, as well as Marshall's Monitor circumaurals, classy Sennheiser open-backs, some Shure IEMs and RHA's flagship earphones. Whatever we used, we were treated to stable, well organized and confident delivery with no discernable distortion.
From the jam-packed board to the rugged and stylish outer housing, the build quality is top drawer. The light show up top isn't just pretty, but offers useful information about the audio running through the device (particularly when plugged into music creation hardware).
We did find the Miyo to be something of a hot potato during use, and the supplied USB cable – with that cool double-sided USB plug – proved a bit of a let-down, but such things were relegated to minor niggles when faced with the impressive sonic performance through dual headphone outputs, the inclusion of a line-level input, and the colorful and useful LED metering.
The Miyo is available now for US$249, which may seem expensive at first glance, but this DAC/amp really does shoot higher than its ticket price. Highly recommended.
Product page: Miyo DAC/amp