Most of my listening time with the HM-101 was spent tethered to a pair of headphones. My reasoning was simple: Most HM-101 users are going to be using it with headphones. The overall sonic signature of the HM-101 is clean, clear, and very direct. With some headphones, such as the AKG K701, the HM-101 sounds slightly thin and lacking in midbass warmth. But when coupled to the HiFiMAN HE-300 headphones, which can sound bass-heavy, especially in the mid-bass, the HM-101 proved to be a synergistic match-up.
Regardless of what headphone or earbud you use with the HM-101, the trick to getting the best performance is to choose an output level that lets you run the slider on your computer’s volume control as close to maximum as possible. I recommend trying the lower level output option first. If you can’t get enough volume, go to the headphone output with 20 dB more gain.
If most of your prior music listening has been through your computer’s built-in sound processing and delivery system the added clarity of the HM-101 will be the first thing you’ll notice. Compared to the HM-101 the sonics from both my PC and Mac portable computers were murky, slow sounding, and lacking in anything approaching dynamic spark. The term “grayish” accurately describes the overall impression of built-in audio compared with the more vibrant, articulate, and involving sound of the HM-101 soundcard.
When I tried the HM-101 in my desktop system I could hear a slight amount of low-level noise when no music was playing and the volume control was set at a normal listening level. The HM-101’s output was not as quiet as that of most of the DAC/Preamps I’ve used recently. And while the sound through the HM-101 was still relatively clean and well defined, it doesn’t have the three-dimensionality or image solidity of the Cambridge Audio DacMagic Plus ($649) for instance. I suspect that some of the HM-101’s dimensionality loss was due to low-level noise obscuring some detail and dimensional cues. However the HM-101 sounded better than the analog output from my MacPro desktop. For most people the HM-101’s best application will be for portable and headphone use rather than in a desktop or room-based system.