Sound Quality - The Bad
We like the HiFiMAN HM-101. Its aims are good, it's a worthwhile product and it's supremely affordable. But it's certainly not perfect.
It adds a noise floor to the signal - a light hiss. Yes, the HM-101 is noisier than a £15 stick MP3 player, and if you exclusively use isolating in-ear headphones, this is a bit of an annoyance. With open-back headphones you can barely hear it, though.
The HiFiMAN HM-101 is also extremely susceptible to interference. Get it too close to a mobile phone or certain other gadgets and it'll start bleating as if it's being touched inappropriately. It's easy enough to get the HM-101 sufficiently far away with a miniUSB cable - if needed you can buy a longer one from eBay for pennies - but only a short one is supplied. And the interference is a reminder that this is in several ways a fairly compromised device.
But let's not forget - it is £30.
Sound Quality - The Good
And for £30, the sound improvements it can provide over a laptop's standard headphone jack are seriously impressive. We tested the HiFiMAN HM-101 with a Windows laptop, a desktop PC and a MacBook Air, all without any special audio hardware. And we tried numerous sets of in-ear, on-ear and over ear headphones ranging from £20 to £600. Some consistent improvements soon became clear.
The HiFiMAN HM-101 excels as tightening-up the low-end and clearing out low-mid bloating, resulting in increased definition and an increased sense of soundstage. Bass volume tends to decrease a bit, which might not be desirable if you're using already bass-light headphones, but response is unmistakeably improved.
Separation and clarity are the staples of "high end" sound, and that a £30 box can provide them is quite remarkable, even if it does introduce noise as part of the bargain. We found the difference in tonal quality more marked than recently-reviewed Fiio models, although in their favour this year's boxes don't add that occasionally irritating hiss.
The HiFiMAN HM-101 is undeniably good value in the same way that Fiio's E6 portable headphone amp is. In this field, anything that provides results at such a low price is worthy of praise. Do consider whether the interference in particular is likely to become a problem, though, as it has the potential to become a deal-breaker.
The HiFiMAN HM-101 is a USB soundcard with a Burr-Brown DAC chip that sells for under £30. And it provides genuine sound quality improvements over a standard computer's audio output. It introduces a little hiss and is terribly prone to interference too, but at the price that it can make a £600 pair of headphones sound demonstrably better is impressive.