Up to 84% in savings when you subscribe to The Absolute Sound
Logo

Begin typing your search above and press return to search. Press Esc to cancel.

Dragon Inspire IHA-1 Headphone Amplifier

Dragon Inspire IHA-1 Headphone Amplifier

Headphone amplifiers come in all sizes and at all prices, from inexpensive project-box designs such as the $129 JPS Labs O2 all the way up to state-of-the-art amplifiers such as the $3995 Audeze “The King.” Right near the middle of this range you’ll find the $1599 Dragon Inspire IHA-1 headphone amplifier, which is sold exclusively by Moon Audio. Created by Dennis Had, the founder of Cary Audio, who has been designing tube-based electronics for over fifty years, the IHA-1 began as a retirement hobby project. Mr. Had sold Cary Audio seven years ago and had planned to do a lot of relaxing and sailing, but after a year the lure of sailing was eclipsed by the siren song of Had’s studio space, where he began working on new single-ended tube designs. Eventually he turned his attention to headphone amplifiers, and the Inspire IHA-1 was born. While its price—especially for what is essentially a hand-built, made-to-order component—places the IHA-1 in the “affordable” category, its performance with the right headphones puts it firmly into the category of something you might buy if price was of no consequence.

Tech Tour
The Dragon Inspire IHA-1 is a single-ended vacuum tube design that has its inputs directly coupled to the grids of two 6SN7 dual-triode tubes with only a selector switch and volume control between the inputs and the tubes. The IHA-1 has only three tubes total in its circuit, two 6SN7 dual triodes and one 5Y3GT rectifier. The IHA-1 can also be configured with different dual-triode tubes, such as a 6BL7 or 6BX7 (with the 6BX7 you lose some output power) and different rectifier tubes, including a 5Y3, 5U4, or a 274B. Because the 6SN7 tube is a dual triode, it allows the IHA-1 to have two gain stages, powered by each section of the 6SN7. While the IHA-1 is not a true dual-mono design because the right and left channels share the same power supply, the two channels remain separated throughout their signal path.

A set of special hand-wound, custom, air-gapped output transformers are also directly coupled to the IHA-1’s outputs. Because the IHA-1 is a direct-coupled design throughout without any coupling caps or output attenuation resistors in the signal path, it is more sensitive to EMF and EMI-generated hum and noise. “Purity at its best” comes at a price, which means you must pay attention to the IHA-1’s physical placement if you wish to hear it sans hum and extraneous noise.

The IHA-1 is also a zero-feedback design. According to the Moon Audio site, “THD is close to ultimate vacuum tube perfection considering zero feedback. The second and all remaining harmonic contents at the 1.125 watt output level into 32 ohms are over 65dB down.” But by eliminating feedback, the IHA-1 design also lacks the noise filtering that feedback can deliver; hence, the IHA-1 will be more sensitive to external noise either through the AC line or from other electronic devices.

The volume control for the IHA-1 is a 100k dual stepped attenuator made by a Danish firm, DACT. While this dual attenuator insures that both channels will track together accurately, it also eliminates the option of any channel balance adjustments. This is the sort of trade-off that was made to optimize the IHA-1’s sonic performance.

Dragon Inspire IHA-1 Headphone Amplifier

Readers may wonder how a single-ended tube amplifier that only supports single-ended inputs can supply a balanced headphone output. The “secret” to the IHA-1’s balanced output operation is that the secondary windings from the IHA-1’s custom air-core transformers are tapped to get the necessary inverted signal for balanced headphone operation.

Physical Setup and Ergonomics
The chassis of the IHA-1 measures 8 inches by 2½ inches (without tubes) by 10 inches, and is finished with a copper powder coat with a dual-process clear coat. The front panel has a volume knob on the left-hand side flanked by a three-way selector (Channel 1, Mute, and Channel 2) to its right. The right half of the IHA-1’s front panel has output connections for single-end ¼” stereo and four-pin XLR balanced headphones and a two-way toggle on/off switch. The back panel of the IHA-1 has two pairs of RCA inputs and one switched RCA output as well as the AC power connection.

The Inspire IHA-1 can be used both as a headphone amplifier and as a two-input analog preamplifier. The line-level output is an additional $100 upcharge over the $1599 base price, but it is an upgrade that vastly increases the IHA-1’s utility. I used both capacities during the review. For part of the review, the IHA-1 was attached to the analog output from a Grace m9xx DAC/pre, which was connected to my MacPro desktop. For some of my critical listening I used several high-performance portable players, including the Astell&Kern AK240, Calyx M, AR M2, Sony NW-ZX2, and Questyle QP1R. Because it has two selectable inputs you could easily set the IHA-1 up to handle both your computer and your portable devices as sources.

I also used a variety of headphones and in-ear monitors with the IHA-1. Since the IHA-1 has both single-ended ¼” and balanced headphone connections I also had the opportunity to compare the single-ended and balanced outputs on several headphones that have interchangeable cables, including the AudioQuest Nighthawk, Sennheiser HD700, and Audeze LCD-2.

My review sample came with two Sylvania 6NS7 dual triodes and one RCA 5U4 rectifier tube. These are the tubes that Moon Audio’s Drew Baird prefers, and they come at an extra cost of $200 (but you still receive the two stock 6SN7 Electro Harmonix and Sovtek 5Y3GT as well). I did not try “tube rolling” (changing out tubes), but obviously being able to use a variety of tubes is part of the appeal of the IHA-1.

 

Sound
The phrase, “the music emerged from an inky black background” has become an audiophile cliché, but after a minute of warm-up (during which you will hear some hum from the right channel), the IHA-1 is as silent, with as quiet a base noise level, as any solid-state headphone amplifier I’ve used. A silent background is even more important in headphone listening than in a room-based system where some small amount of hum and noise can be forgiven because it’s inaudible by the time you move far enough away from the loudspeakers to listen. With headphones you can’t rely on distance to reduce a system’s intrinsic noise level.

When I received the first sample IHA-1, it had a hum that would not go away regardless of placement or AC wiring scheme. I returned it for a second sample. The second sample was hum-free as long as it was properly placed and connected (it was especially sensitive to noise generated by some AC power conditioners such as the EquiCore 150 balanced power conditioner, which I’ve found is best reserved exclusively for digital devices). With the PS Audio Quartet, the IHA-1 was absolutely silent when used as a line-level preamplifier or headphone amp, even with the volume control turned up all the way to full output, which is how I sometimes used it with the Grace M9xx, where I relied on the Grace’s volume control with its finer delineations to attenuate levels.

Some headphone amplifiers are designed to be general-purpose devices, with multiple gain and impedance adjustments, while others are made to work best with certain headphones that fall within a more limited specification set. The IHA-1 is definitely one of the latter. Dennis Had told me that the two headphones he used when designing the IHA-1 were the Grado PS-1000 and Audeze LCD-3. My experience is that the IHA-1 is better suited for medium- and low-sensitivity headphones than anything with sensitivity greater than 90dB. With higher-sensitivity in-ear monitors, the IHA-1 has a noticeable hiss that obscures low-level details. Some of the headphones that were too noisy for my tastes included the Oppo PM-3, Audeze EL-8, and virtually every in-ear monitor in my collection.

Once you eliminate all the higher-sensitivity headphones that don’t mate well with the IHA-1, you’re still left with a plethora of ’phones that do. Among those that worked successfully with the IHA-1 were the Sennheiser HD-600, Sennheiser HD-700, Audeze LCD-2, Beyer Dynamic DT-990 600-ohm version, HiFiMan HE-560, Beyer Dynamic DT-880 250-ohm, AKG K-7xx, AKG K-553, Grado RS-1, AudioQuest Nighthawks, Mr. Speakers Alpha Primes, and Audio Technica ATH-A900x.

Once it is mated with a headphone for which it is suited, the IHA-1’s midrange liquidity and innate harmonic beauty will roll over you like a fifty-foot wave. The IHA-1’s midrange is lush without sounding thick, fast without losing lower-midrange body, and immensely musical. But like all single-ended designs, this midrange purity comes at a price—less control and definition at the frequency extremes. While I found the IHA-1’s treble response exhibited no noticeable sonic failings, its bass response was fluffier and less incisive than more conventional tube and solid-state headphone amps I’m familiar with. I call this “marshmallow bass.” Headphones with large suspended planar drivers had the most noticeable issues from the IHA-1’s lack of low bass damping, but on other headphones, such as the AKG K-7xx, the differences in low-bass presentation were reduced.


Dragon Inspire IHA-1 Headphone Amplifier

The three-dimensionality of the IHA-1’s soundstage, especially when the unit was coupled to a spatially incisive headphone such as the HiFiMan HE-560 or the Grado RS-1, was something akin to wandering around in a huge hall that just happened to be inside and around your head. And while even the “lowly” O2 headphone amplifier can deliver precise lateral imaging and a decently sized soundstage, the IHA-1 takes that lateral image specificity and adds another dimension—depth—and then explodes the soundstage outward, leaving plenty of room for the spaces between the notes as well as among the instruments themselves.

With most solid-state headphone amplifiers the balanced output has double the voltage swing of the single-ended output because it is using two amps (one in positive polarity and one with inverted polarity). The IHA-1 does not double the voltage swing because it uses the same amp, creating the balanced signal with its transformer-coupled output. By the very nature of the output transformer, a balanced signal appears at the secondary output winding so there is no need for a phase inverter or second amp section.

Given that the balanced output does not offer additional voltage, I found that using a balanced cable instead of a single-ended one from the same manufacturer (Wireworld) resulted in no audible differences between the two connections with all three headphones I used for this test—the AudioQuest Nighthawk, Sennheiser HD700, and Audeze LCD-2.

When I used the IHA-1 as a preamplifier, I was most impressed with its soundstaging and imaging characteristics. When compared to the Grace m9xx’s preamplifier section, the IHA-1 produced a slightly larger stage overall with remarkably specific three-dimensional imaging on phase-coherent recordings. I was also captivated by the IHA-1’s lack of background noise or low-level hum. Finally, the IHA-1’s bass was not as soft and fluffy when used as a preamplifier. Although the IHA-1’s midbass was slightly less taut than that of the Grace m9xx, on some selections I preferred the IHA-1’s softer yet fuller bass response.

The perennial question in the tubes-versus-solid-state amplification debate is whether tubes are subtractive, removing some amusical energy that solid-state passes on to your ears, or if tubes merely have fewer additive distortions than comparable solid-state devices. Depending on the particular tube and solid-state circuits involved, the answer could be either or both. But when used in an optimal setup, with a high-performance headphone, the IHA-1 makes a strong sonic argument for a single-ended tube design as a lower-distortion (when not stressed) and less sonically pernicious technology.

 

Competition
There aren’t a lot of single-ended tube headphone amplifiers currently in the market, but one that does compete with the IHA-1 is the Woo Audio WA7 Fireflies with tube power supply ($1398). The Woo can handle a wider range of headphones than the IHA-1 (it can be used with sensitive in-ears without adding noise). It also has a decent USB 2.0 input to handle digital feeds up to 192/24. The downsides of the Woo compared to the IHA-1 are that the Woo does not offer a balanced XLR connection and it can’t function as a preamplifier. I did not have a WA7 in my possession during the IHA-1 review to make any direct sonic comparisons.

Although it’s solid-state, the NuPrime DAC-10H has a similar price ($1795) and feature set. Both units can handle single-ended and balanced headphones and both can also serve as preamplifiers. The DAC-10H does have greater flexibility than the IHA-1 with more inputs (including analog line-level) and outputs as well as a very good DAC capable of 384/32 PCM and DSD128. The DAC-10H can also handle a wider range of headphones successfully. Sonically, the DAC-10H offers a clean, clear, more matter-of-fact solid-state view of the musical event as compared to the IHA-1’s tube-centric three-dimensional panorama.

Summary
As I said at the beginning of this review, nowadays audiophiles have a multitude of options when it comes to headphone amplifiers, from USB-stick-sized units for $100 to multi-functional full-sized components with six-figure price tags. Even within the limited range of $1500 to $2000 you will find almost every type of headphone amplifier, but none offers quite the same combination of sound and features as the Dragon Inspire IHA-1. If you’re in the market for a single-ended, directly coupled, all-tube headphone amplifier with the ability to function as a low-noise line-level preamplifier you should seriously consider the IHA-1. And while sonic purity comes at a price, in the IHA-1’s case that price is far less than you would expect for a hand-built, point-to-point-wired, U.S.A.-made component.

SPECS & PRICING

Input impedance: 100k purely resistive
Frequency response: 12Hz to 32kHz +/-0dB
Power output into 40 ohms: 1.7W at less than 1% THD (primarily 2nd harmonic) 
Amplifier gain: 18dB
Noise floor: 87dB
Headphone outputs: 1/4″ single-ended and 4-pin XLR
Output tubes: Two 6SN7 dual triodes
Rectification: One 5Y3
Dimensions: 10″ x 6″ (with tubes installed) x 8″
Weight: 12 lbs.
Price: $1595 base price (NOS tubes, $100; switched line-level output, $100)

MOON AUDIO
106 Brady Ct.
Cary, NC 27511
(919) 649-5018
moon-audio.com

Read Next From Review

See all

Adblocker Detected

"Neque porro quisquam est qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit..."

"There is no one who loves pain itself, who seeks after it and wants to have it, simply because it is pain..."