Moon Audio Dragon Inspire IHA‑1 headphone amplifier

This review centres on the Dragon Inspire IHA‑1 valve-powered headphone amplifier, which is produced by the Cary, North Carolina-based firm Moon Audio (www.moon-audio.com). Those of you already familiar with Moon Audio may know of the firm as an internationally recognised retailer of all things related to personal audio and as the maker of a respected line of high performance audio cables. However, what some may not know is that Moon also manufactures a specialised range of personal audio electronics components, the flagship of which is the Dragon Inspire IHA‑1.

Hi-Fi+ Editor Alan Sircom and I both encountered the Dragon Inspire IHA‑1 for the first time at the CanJam London event held in the summer of 2016, when Moon president Drew Baird pulled us aside to hear his amplifier driving a set of Focal’s spectacularly good Utopia headphones. Moon Audio’s demonstration station was positioned directly across from the Focal/Naim demo area, which meant that we could (and did) take the opportunity compare the sound of the Utopia headphones driven by Naim’s solid-state electronics to the sound of the same headphones powered by Baird’s hand-built, valve-powered amplifier. Our take was that the Utopia sounded superb in both contexts, but that it seemed to come alive in an almost magical way when driven by the USA-made valve-powered amplifier. So, at that very moment, the idea for this review was born.

Before we proceed, though, let’s clarify a few key points. First, Moon Audio should not be confused with the similarly named Canadian firm Moon by Simaudio, which makes some very fine headphone amplifiers (and other high-end audio electronics) in its own right. Second, be aware that Moon’s Dragon Inspire IHA‑1 comes with a serious high-end pedigree, in that it was designed by (and is manufactured under the watchful eye of) none other than Dennis Had—a man perhaps best known as the founder of Cary Audio. (Cary Audio, though not necessarily as well known in the UK as it is in US, is a firm whose predominantly valve-powered electronics components have earned an enviable reputation both for exquisite workmanship and especially for their effortless and elegant musicality).

Up front, the IHA‑1 sports a DACT 100K stepped attenuator driving a pair of 6SN7 power output valves. The amplifier is direct coupled meaning, says Moon, that the “input driving signal is directly coupled to the grids of the 6SN7 dual triodes.” Moon goes on to say that, “this signal is amplified and sent to the headphones through a special set of hand wound air-gapped output transformers,” meaning there is, “direct coupling straight through to the headphones.”

This configuration reflects Dennis Had’s preference for straightforward and effective circuit topologies where, in Moon’s words, the “main concern is always the sonic purity of the output signal as perceived by the human ear.” The amplifier uses zero negative feedback—a design choice that foregoes flashy distortion specifications in favour of achieving greater perceived sonic purity. Nevertheless, the amplifier delivers very respectable distortion measurements, so that according to Moon, “the second and all remaining harmonic contents at the 1.125 Watt output level into 32 Ohms are over 65dB down.”

On the power supply side of things, the IHA‑1 uses what the manufacturer describes as “tube rectification with dual filter chokes to provide a low noise level along with a low impedance B+ power supply to the 6SN7 tubes.” The intent is not so much to give the amplifier vast power output capabilities, per se, but rather to provide “vacuum tube amplification in the purest form.”

For my listening tests, I used a Windows/Lenovo/jRiver-based music server feeding a Questyle DAC, which in turn fed the inputs of the Dragon Inspire IHA‑1. I also had on hand a brace of superb headphones including the Focal Utopia (fitted with Moon Audio’s Dragon Premium cables), the HiFiMAN HE1000 v2 (fitted with Nordost Heimdall 2 cables), the MrSpeakers ÆON headphone with stock cables, and the MrSpeakers ETHER Flow (fitted with Kimber Axios cables). Armed with these excellent ancillary components, I set to work to gather notes on the sound of the Dragon Inspire IHA‑1.

Moon Audio had graciously supplied both a set of stock valves (6SN7’s from Electro Harmonix and a Sovtek 5Y3), plus a set of NOS valves. The amp sounded fine with its standard valves, though I would say its sound reminded me somewhat of the taste of an excellent but young Cabernet Sauvignon (in other words, a sound that was promising, but not quite there yet). With the NOS valves in place, the sound became analogous to the richer, more well rounded, and more complex taste of a fully mature Cabernet, which was satisfying indeed. For obvious reasons, then, I did most of my listening with the NOS valves installed.

From the outset, I found the IHA‑1 served up an uncommonly rich, sumptuously detailed, and evocative sound that offered musical benefits galore. Now to speak candidly, when audio journalists invoke words such as “rich”, “sumptuous”, or “evocative”, this often means they are describing components that produce pleasant sounds, but that might possibly be tinged with faint traces of euphonic colouration. But that isn’t the case at all with the Dragon Inspire IHA‑1; on the contrary, it’s sound seems admirably neutral in overall balance, yet it manages to strip away virtually all those sonic artefacts that—in some amplifiers at least—tend to impart a subtle quality of sterility that overlays the music and robs it of some of its natural beauty. As you listen through the Moon, you soon discover that it has banished the mechanical-sounding and sterile qualities that afflict some amplifiers, so that the effortless emotional expressiveness and the organic (not artificial) warmth of music are more fully revealed.

To get a taste of the qualities I am describing, try listening to “The Curse” from Agnes Obel’s Aventine [Play It Again Sam, 16/44.1], focussing on the lilt of Obel’s voice and on the timbres of the accompanying cello. Obel’s voice, much like Leslie Feist’s, is one whose upper registers can at their best sound beautifully delicate and pure, but with upper harmonics that—through some amplifiers—can potentially become brittle and shrill. Through the Moon, though, you get only the soaring, upward-reaching beauty of the voice with essentially zero brittleness or shrillness, which is as things should be. On the accompanying cello, the Dragon Inspire deftly captures both the physical size and sheer ‘woodiness’ of the instrument’s sound. Where some amps tend to make cellos sound like overgrown violas, the Moon neatly reveals the impressive upper range of the cello while at the same time gently reminding you that the instrument has substantial size, depth, and that gloriously rich quality of woody sonority. This sort of continuing discovery of the true, pure timbres of human and instrumental voices is perhaps the best reason of all to consider owning the Dragon Inspire IHA‑1.

Two other reasons, though, would be the amplifier’s remarkable three-dimensionality and unconstrained dynamics. One quality the IHA‑1 consistently delivers is a heightened sense of spaciousness that applied with all of the headphones I tried, but that was perhaps most noticeable and beneficial with the Focal Utopias. Through the Moon, the soundstaging capabilities of the headphones in play are suddenly stretched outward and in some cases forward, so that the music can unfold on much larger stage. On ‘Nublado’ from Sera Una Noche [MA Recordings, 16/44.1], for example, the Moon amp lets you hear a seductive Argentine tango expand within a spacious and reverberant space that extends far beyond the confines of one’s own head. This same ‘music unchained’ quality extends to dynamics, too, so that the Moon gives everything from delicate individual notes to large orchestral swells all the space and power they need in order to breathe.

The bass performance of the IHA‑1 offers plenty of power and depth, as I learned when taking in the low rumblings heard on Massive Attack’s ‘Angel’ from the album of the same name [EMI, 16/44/1]. The only minor drawback is that the amp does not deliver quite the same levels of low-end ‘traction’ or ‘grip’ that some solid-state amplifiers do, although in fairness this only becomes noticeable when listening through headphones whose bass is perhaps slightly under-damped. With well-controlled headphones, and in particular through the Focal Utopia, the Moon’s low-end sounds nearly perfect, with just right touches of weight, warmth, and pitch definition.

If I sound impressed by Moon’s Dragon Inspire IHA‑1, that’s because I am. What we have here is in essence a handmade, bespoke-quality headphone amplifier that sells for well under $2,000. Most importantly, it consistently does justice to the music in ways large and small and that make you want to listen and keep on listening. Isn’t that precisely what a top-class headphone amplifier should do?

TECHNICAL SPECIFICATIONS

Type: Valve-powered headphone amplifier/preamplifier


Valve complement: Two 6SN7 dual triode power output valves, one 5Y3 rectifier valve as standard. The amplifier supports ‘tube rolling’ and can be supplied with New Old Stock (NOS) 6BX7 power output valves and with a 274B rectifier valve for a nominal upcharge.

Inputs: Two stereo single-ended inputs (via RCA jacks)

Outputs: One single-ended stereo headphone output via a pro‑style locking 6.35mm TRS-type headphone jack, one stereo “Transformer Pro Balanced” headphone output via a 4-pin XLR jack, one single-ended stereo preamp output via RCA jacks.

Frequency response: 12Hz–32kHz ± 0dB with no negative feedback

Noise floor: –87dB


Power Output: 1.7 Watts @ 40 Ohms, <1% THD 2nd harmonic

Dimensions (H×W×D): 6” × 10” × 8” (with stock valves installed)

Weight: 15lbs

Price: $1,599; upgrade to NOS 6BX7 power output valves +$100; upgrade to 274B rectifier valve +$160

Manufacturer Information: Moon Audio
106 Brady Ct., Cary, NC 27511 USA

Tel.: +1 (919) 649-5018

URL: www.moon-audio.com

Note: Although Moon Audio is a US‑based firm it routinely arranges sales and shipments to the UK and to Europe. Contact Moon Audio for details.