The sound of the GT40 is characterized by:
• A nicely balanced, ever-so-slightly midrange-forward sound that is full of openness and sonic nuance. The GT40 sounds slightly more lightly balanced and midrange centric than does, say, a well broken-in sample of the NuForce Icon HDP (which has a slightly darker presentation overall), though in terms of absolute clarity and transparency I would give the nod to the GT40.
• Bass is very good, too, though the GT40’s low-end prowess hinges more on pitch definition and the ability to capture delicate (and in my experience often quite elusive) textural elements that nicely reveal the more expressive qualities of low-frequency instruments. In terms of bass power, the GT40 can arguably be equaled or even surpassed by similarly priced competitors (e.g., the NuForce Icon HDP, priced at $449), but the GT40’s textural refinement is a rare thing to behold (at least for products in this price class).
• Refinement: there is a certain suave, sophisticated quality to the GT40’s overall presentation that creates the sense that music simply flows freely out of the little silver box in an effortless, unconstrained way (this in contrast to some moderately priced amp/DAC combos that sound—in subtle ways, of course—as if they are “working hard” to do the things that they do). The bottom line is that the GT40 offers up a quality of graceful ease that, to my way of thinking, is one of its most appealing aspects (it’s a quality that, for my tastes at any rate, just makes me want to keep listening through the GT40).
In an absolute sense, the GT40 does not have the ultra-stout drive characteristics of, say, more costly headphone amps such as the Burson Audio HA-160, the Apex Peak/Volcano, or the Cavalli Audio Liquid Fire. But it comfortably holds its own with comparably priced competitors, offering plenty of output for moderately sensitive headphones (e.g., the delightful new Audio-Technica ATH-W1000X “Grandioso”) while holding enough power in reserve to drive such admittedly power-hungry headphones as the HiFiMAN HE-5LE’s. When you do plug in ‘phones that like power and lots of it, just be aware that you’ll need to turn the GT40’s gain knob up pretty far in order to get adequate output levels.

The Furutech/Alpha Design Labs GT40 will become the subject of a full-length Playback review in the not-too-distant future, by which time we’ll be able to give more in-depth comments on the GT40’s phono section and capabilities as a digital recording interface. In the meantime, I hope this blog will encourage you to seek out this fascinating product and to give it a listen so that you can form your own impressions. It does an awful lot for a not unreasonable sum of money.
Until next time, happy listening.