At this point in history, there is simply no good reason that people aren't getting excellent sound out of their computers. It's obscene and absurd that computers don't come equipped with capable converters, clocks, line amps, and headphone amps; and it's even worse that so many people willingly accept this lame sound as the centerpiece of their listening and recording systems. We humans totally favor the visual over the aural — new iMacs with Retina 5K displays have 14,745,600 pixels, but the same computer's audio output remains granular at best, collapses the stereo image and soundstage, and is annoying to listen to for long stretches of time. Popular interest in hi-fi took a nosedive during the '90s, and today's listening culture is needlessly clinging to the horrible ethos of convenience-over-quality. How can listening culture be so out of step with what modern digital audio technology has to offer? How can the world's fastest, smallest, most powerful electronic devices still ship with shit-fi sound?
Because of this completely idiotic situation, some audio companies have developed high- quality external converters and headphone amps. There are big ones and little ones; expensive ones and cheap ones; good, great, and iffy ones. A quick perusal of what's available is pretty daunting. For those of us doing any compact, mobile recordmaking, however, MIYO - a DAC, ADC, and headphone amp in a tiny, USB-powered package — is the obvious choice.
MIYO only costs $250, but if you were to just listen to it blind, you'd swear you were hearing something bigger and more expensive that was plugged into a wall. The soundstage, imaging, and clarity are phenomenal, and it is never annoying or fatiguing during long listening sessions. It's so much better than the stock crap on my MacBook, that a non-expert, non-audiophile — just a regular schmoe — recently said, "Holy shit!" when I swapped out the Apple-crap for MIYO.
Yes, details matter. Resolution matters. Clocking matters. Conversion matters. Amplifier quality matters. It all matters, especially when you add all that up. It matters if you're a schmoe blowing some of your precious time on this planet listening to records. And it especially matters if you're a professional recordmaker executing crucial sonic decisions.
MIYO is beautiful, slick, solid, small, silver, and loaded with good components and features. It employs asynchronous USB mode, which means that you're using MIYO's onboard clock to set the 0s and 1s onto a superior clock reference signal, in this case generated by two discrete microelectromechanical systems (MEMS) oscillators achieving 0.5 ps RMS phase jitter (that's really low). Sample-rate support is up to 24-bit, 192 kHz. Furthermore, MIYO's two headphone jacks are powered separately, so they won't falter when both are used, and the total output is 1.5 W. These amps handle headphones with impedances reaching down to 8 Ω, and MIYO had no issues driving the heck out of all cans I plugged into them. Paired with my Focal Spirit Professional headphones, I've got "reference grade" monitoring in my carry-on. Both headphone jacks also double as digital outputs, incorporating optical ports inside them (just like the mini-TOSLINK-compatible headphone jacks on most Macs).
The stereo input is unbalanced and on an 1/8'' jack, but with an impedance of 4.76 kΩ and a maximum input level of +12 dBu, you can use it to record high-Z line-level signals, no problem. No other portable DAC that I've found includes a high-quality ADC as well, putting MIYO in a class of its own that's ideal for recordmakers.
And here's another very important feature: MIYO takes over your computer's digital volume control and uses it to adjust MIYO's onboard analog attenuator — a nice trick. This really matters, because digital attenuation lowers bit-depth and causes music to sound thin, crinkly, and aliased — it's just really awful. With MIYO, you lose nothing but volume when you turn down the computer's onboard level control.
The onboard metering is good-looking, very intuitive, and useful; but the details of how it works are slightly complex to explain, so I'll let you read about that on your own on the product website.
I have only two complaints about MIYO. First, it gets really hot, so while it dangles against my leg or arm, I am sometimes quickly brought to alertness. Second, it won't work directly with my phone or iPad, because MIYO requires more USB bus power than these portable devices can supply. (An inelegant workaround utilizing a powered USB hub is described on the product website.)
If you're doing portable audio work and using the crap-verters and poop-amps in your laptop, I strongly suggest that you immediately get a MIYO, start evangelizing great sound at your own portable hi-fi revival meetings, and fervently demand that your collaborators, family, friends, and complete strangers plug into the second headphone jack of the MIYO and finally hear what records are supposed to sound like. If we recordmakers aren't actively proselytizing for great sound, how can we expect the listening culture to ever evolve out of the Digital Dark Age and enter The Hi-Fi Renaissance? If we can't play back stunning sound, how can we proselytize? Or even just do good work? Bravo Team MIYO on a great product — and for having the vision to make it.