During the pandemic, I became enthusiastic about brewing my own coffee at home. I’d twist myself into knots trying to figure out which brewing method suited me best and what all the flavor profiles on packaging and in reviews meant. Terms such as “acidic,” “sweet,” and “full-bodied” sounded descriptive enough—but acidic, or sweet, or full-bodied compared to what, I wondered. Then there were admonitions to use light roast for this, medium roast for that, and dark roast for something else. With experience, I have found that espresso is my preferred brewing method, and learned that there is no such thing as an espresso bean.

The world of digital-to-analog converters seems similar—overanalyzed yet oversimplified. Like fourth-wave coffee, iFi Audio’s products are very popular; they’re highly regarded for their sound quality, build quality, and accessible pricing. Priced at $1299 (all prices in USD), the iDSD Diablo 2 is iFi’s flagship portable DAC–headphone amplifier. With its bright-red finned chassis, the Diablo 2 is a very striking piece of kit—the moniker “Diablo” fits perfectly. And underneath that flashy exterior is some very slick technology.

You can use the Diablo 2 for headphone listening, at home or on the go. Or you can connect it to an amplifier or a pair of active or powered speakers for out-loud listening.

Outside . . .

iFi rightly describes the Diablo 2 as “more transportable than pocket sized.” Measuring 1.1″H × 3.3″W × 6.5″D and weighing one pound, the unit could fit in a pocket, but it would have to be an overcoat pocket. For portable use, the Diablo 2 has a 4800mAh lithium-polymer battery, which is charged from one of the unit’s USB-C ports. The battery is rated to provide 6 to 12 hours of playback time, depending on operating mode.

Constructed from machined aluminum, the crimson chassis has an elongated hexagonal shape, with 22 grooves that aid in heat dissipation. Eight of those grooves also function as rails for the supplied slotted stands, or “wings,” as iFi calls them. These can be used to support the Diablo 2 horizontally or vertically on a desk or similar surface. I placed the Diablo 2 vertically on my desk, which was a great way to save space.

In addition to the stands, the Diablo 2 comes with an iPower 2 USB-C 5V power supply–charger, a USB-C cable, a USB-C-to-A adapter, a USB-C-to-Lightning adapter, a TosLink-to-3.5mm adapter, a 3.5mm-to-6.35mm (1/4″) headphone adapter, and a carrying case. iFi says the included iPower power supply has noise-cancellation circuitry that improves sound quality when the Diablo 2 is being powered from an electrical outlet.

On the left side of the front panel is a 6.35mm single-ended headphone output, and just down and to the right is a 4.4mm Pentaconn balanced headphone output. Above the balanced output jack is a switch for using the Diablo 2 with xMEMS earphones. MEMS (Micro-Electromechanical System) is an emerging technology that uses an inverse piezoelectric effect to produce sound.

In the center is a switch for operating mode. There are three options: Normal, for use with high-sensitivity in-ear monitors; Turbo, for use with medium-sensitivity headphones; and Nitro, for use with demanding, low-sensitivity ’phones. With conventional (non-xMEMS) headphones, playing time under battery power for the three modes is 12 hours, 9 hours, and 6 hours, respectively. Further to the right is a status LED that illuminates in different colors and patterns to show the input, Bluetooth mode, and resolution.

The volume knob on the far right has a good feel and turns very smoothly. But it was not firm enough to stay in place when it encountered slight friction while the amp was in my pocket. iFi offers an elegant solution—a lock to the left of the knob that prevents the volume knob from moving. The volume knob also serves as the power-on switch with a firm turn to the right.

When listening through very sensitive IEMs, you can use the iEMatch switch on the bottom to reduce output level by 6dB or 12dB. Around back is a button for Bluetooth pairing and input switching, a 4.4mm jack that can function as a balanced line-level output or a single-ended line-level input, a 3.5mm input jack that can accept line-level analog or S/PDIF audio, a USB-C port for the power adapter (and below it, a battery-status LED), and a USB-C data port for receiving audio data from a smart device or personal computer.

. . . And inside

One of the most important differences between the original iDSD Diablo and the Diablo 2 is the new model’s Bluetooth connectivity, which means you do not need a wired connection to the source device. This feature wasn’t offered on the original Diablo. And the Diablo 2 features state-of-the-art Bluetooth 5.4 connectivity, with support for advanced codecs like aptX Adaptive, aptX Lossless, aptX HD, LDAC, and HWA/LHDC.

Particularly notable is the unit’s support of aptX Lossless, which allows CD-resolution streaming with no lossy compression. Currently, there are only a handful of smartphones that support this codec, but that list will undoubtedly grow. But if you want to stream wirelessly from a smart device to the Diablo 2, the Diablo 2 will use the most advanced Bluetooth codec supported by your device.

I suspect most owners of the Diablo 2 will use one of its wired inputs: analog, S/PDIF, or USB-C. The Diablo 2 supports resolution up to 32-bit/768kHz PCM and DSD512 via USB and up to 24/192 PCM via S/PDIF. It can perform full decoding and rendering of MQA files.

Incoming digital audio is processed by a 32-bit, 16-core XMOS Cortex controller running code that iFi claims maximizes the performance of the unit’s dual-core Burr-Brown DAC. According to iFi, the DAC’s dual-chip “interleaved” configuration minimizes noise, improves channel separation, and enhances detail retrieval. The Diablo 2 employs iFi’s GMT (Global Master Timing) femtosecond-precision digital clock to minimize jitter. Different pathways are used for PCM and DSD streams.

Rated output of the Diablo 2’s headphone amplifier is 2450mW into 32 ohms or 153mW into 600 ohms through its single-ended output, and 5180mW into 32 ohms or 611mW into 600 ohms through its balanced output. Premium parts are used throughout, including an analog volume control, custom MOSFET op-amps in both the analog and digital sections, and hand-selected premium capacitors.

Setup

Since this review is appearing on SoundStage! Hi-Fi rather than SoundStage! Solo, I wanted to use the Diablo 2 as a source component in my reference system. But I also wanted to use it as a headphone amp.

The heart of my reference system comprises a Simaudio Moon 390 streaming DAC–preamp, which is connected to a Simaudio Moon 760A power amplifier with Kimber Kable Select KS 1116 balanced interconnects. My Klipsch Forte III speakers are connected to the 760A with Kimber Kable Ascent TC series 8TC speaker cables. My music library resides on an Innuos Zen Mk3 music server, which is connected to the Moon 390 with an AudioQuest Coffee USB cable, but I also stream to the Moon 390’s MiND module. The Moon 390 has a phono stage, but for this review, my vinyl rig sat idle. All components were plugged into an AudioQuest Niagara 1200 power conditioner, which was connected to an AC outlet with an AudioQuest Thunder power cable.

For both headphone and out-loud listening, I played music using the Roon ARC app on my iPad and iPhone 13 Pro, which I connected to the Diablo 2 using the supplied Lightning-to-USB cable. For headphone listening, I used my Audeze LCD2 Closed-Back headphones.

Setting up the Diablo 2 for out-loud listening was made complicated by the unusual cable required. To connect the Diablo’s fixed line-level output to my Moon 390, I ordered a Youkamoo 4.4mm-to-dual-XLR cable from Amazon. While I waited for it to arrive, I connected the 3.5mm headphone output to the Moon 390 with a 3.5mm-to-dual-RCA cable, and maxed the Diablo 2’s volume setting so that the Moon 390 would receive an adequate signal.

Trouble in paradise

This temporary setup proved less than ideal. Fed to my Moon 390 from the 3.5mm headphone output, the sound seemed etched, with exaggerated high frequencies, recessed mids, and wooly bass. For example, on Medasin’s “Leaving Earth 2” from their album Irene (16-bit/44.1kHz FLAC, Vision Records / Tidal), the opening choral vocals were muted in comparison to the upper and lower frequencies. The keyboard was out of balance with the cymbals and drums, which had a slightly bloated feel.

I wondered if an acoustic selection like Fink’s live album Wheels Turn Beneath My Feet (16/44.1 FLAC, Ninja Tune) would suit the Diablo 2 better. But Fink’s voice’s dark coloring and strained rasp up top left his vocals with a hazy, strained quality. His guitar plucks sounded sterile. The soundstage height was lower than anticipated. There was little air between the instruments, which detracted from the feel of the live recording.

So, I put things aside and waited for Amazon to deliver that Youkamoo balanced cable. After it arrived, one of the first tracks I played was “Rain” by Nicole Bus from her album Kairos (24/44.1 MQA, Roc Nation / Tidal). This is one of my go-to tracks. The overall presentation was pleasant, but even with the new cable and more appropriate line-level connection, I found the sound of Bus’s voice a bit colored, and the timbre of the piano unconvincing. The soundstage was also slightly confined in height, width, and depth.

What was up? Had I made a mistake by going cheap? Instead of ordering from Amazon, should I have bought the cable offered by iFi at twice the price? Or was the Diablo 2 more suited for headphone listening than integration into a two-channel hi-fi system?

Blossoming

Consumed with these worries, I just let the Diablo 2 play music from Roon Radio in the background for a few days. Then something happened. I heard a guitar pluck that sounded just right—rich and layered rather than sterile. I knew the Diablo 2 had blossomed. I was so excited that I forgot to check what song was playing. This was a light-bulb moment.

To kick off this new chapter of my saga with the Diablo 2, I cued up the remastered version of Madonna’s 1990 compilation The Immaculate Collection (16/44.1 MQA, Sire / Warner Records / Tidal). “Vogue” is one of my favorite tracks from this album because of its explosive start. I find it valuable for determining imaging specificity and soundstage height and depth. The Diablo 2 did a wonderful job with the placement of instruments and voices. Madonna’s vocals were front and center, as expected, with background vocals coming from behind her. While the soundstage had satisfying height and width, it was not as expansive as I have heard on this song through my Klipsch Forte III speakers. I also found the dynamics slightly compressed, such that the explosive parts of the song sounded a bit too relaxed. Still, I really enjoyed what the Diablo 2, with its newfound bloom, did with this song.

Another favorite album is My Soft Machine (Deluxe) by Arlo Parks (24/44.1 FLAC, Transgressive Records / Qobuz). I especially like the track “Impurities.” The Diablo 2 gave Parks’s vocals a smooth and relaxed presentation that I found engaging. The soundstage was broad and high, but a bit shallow, so that the keyboard seemed to be on the same plane as the vocals. Even with the limited depth, instrumental separation was good, meeting my expectations for this track. Bass had good slam and punch, but I would have liked to hear a little more definition. I knew my Forte III speakers were capable of delivering more textured bass on this track.

Comparison

I compared the Diablo 2 with two other DACs: the one built into my Moon 390, and a Chord Electronics Qutest DAC ($1595), which was connected to the Moon 390 with Shunyata Venom RCA interconnects. I streamed to the Moon 390 via Roon, as it is Roon Ready. For the Qutest, I used the Roon ARC app on my iPad, which was connected to the DAC’s USB input.

The first 30 seconds of “Video Games” by Lana Del Rey (Born to Die, 24/44.1 MQA, Polydor Records / Tidal) were very revealing of the differences between the Diablo 2, the Qutest, and the DAC built into my Moon 390. The track opens with a bell ring and solo harp, and then Del Rey’s vocals begin. With the Qutest, I noticed sharper focus and faster dynamics compared to the Diablo 2. The initial plucks of the harp and ensuing resonance of the harp body were more clearly delineated. Through the Chord DAC, Del Rey’s vocals were locked in the center of a soundstage that extended well above and beyond my Forte III speakers. Through the Diablo 2, the soundstage was more constrained and there was less air around the instruments.

The Moon 390’s DAC created a soundstage that was taller, wider, and deeper than those thrown by the Diablo 2 and the Qutest. Del Rey’s vocals had great focus and clarity. Leading edges of instruments like the harp and bell were not as crisp as they were through the Qutest, but I found the 390’s presentation smoother, more relaxed, and less fatiguing—the Chord DAC was occasionally overwhelming in the way it emphasized detail. The Diablo 2 had a similarly relaxed presentation, but with a bit more high-frequency energy.

Through the Diablo 2, Chris Stapleton’s subtle electric guitar strumming on “Death Row” (From A Room: Volume 1, 24/96 FLAC, Mercury Nashville / Tidal) sounded crisp and wonderfully textured. Subtle details in his playing were present, but not pushed forward. Through the Qutest, I heard greater dynamic swings. Both the Diablo 2 and Qutest threw a soundstage that extended beyond the bounds of my Klipsch speakers, but the soundstage created by the Qutest was wider and taller. The Moon 390 created a soundstage that was even wider still, and reproduced drums with greater weight and punch.

Headphones

Evaluating the Diablo 2 as a DAC–headphone amplifier was much easier than evaluating it as a source component in my two-channel rig. I simply plugged my Audeze cans into the unit’s 6.35mm unbalanced headphone output. I used the Diablo 2 with battery power, playing music from my iPhone Pro 13 using the Roon ARC app, and compared its performance with the headphone amplifier built into my Moon 390. In Turbo mode, the Diablo 2 drove my Audeze headphones with ease—which is impressive, as they are known to be a demanding load.

I can listen to the title track of East Atlanta Love Letter by 6LACK (24/44.1 MQA, LVRN Records / Tidal) on repeat because of its infectious pace and rhythm. This ballad strikes an emotional chord that I cannot ignore. A nostalgic, evocative keyboard introduction leads to the American rapper’s vocals, first recited and later sung, in the center of the soundstage, with fellow rapper Future ad-libbing in an arc that seems to circle through the background. This adds an element of depth and air to the whole production, which is supported by deep, impactful bass.

I was surprised by how good 6LACK and Future sounded through my Audeze ’phones when powered by the Diablo 2. Even at low listening levels the dynamics were compelling, with brilliant highs complementing powerful bass.

The Moon 390’s headphone amp didn’t have the drive needed to make my Audezes shine on this track. Compared to the Diablo 2, everything seemed dialed-back and lethargic, as if a veil had been placed over the entire presentation. The piano in the beginning seemed pushed back in the soundstage, giving me the urge to turn up the volume to pump more life into the song.

On the title track of Naif by Afterlife (24/44.1 FLAC, Subatomic UK / Qobuz), the bass line had greater texture and faster attack with the Diablo 2 powering the Audezes. With the Moon 390 driving these big planars, the bass line lacked grunt. The Diablo 2 created a soundstage that was just as wide and deep as the one created by the Moon, but there was a little less air between the instruments.

Conclusion

I found these comparisons revealing. For out-loud listening, I preferred the Chord Qutest and the DAC built into the Moon 390 to the Diablo 2—but not by a huge margin. The Chord DAC extracted more detail from the recordings I listened to, especially recordings of complex electronic music. But this sometimes came at the expense of instrumental weight. This was especially noticeable on pop, R&B, and hip-hop tracks, where the Diablo 2 shone. The Moon 390 was my favorite of the three, combining clarity, weight, and ease of delivery with all types of music. But the fact is that parsing out these sonic differences required extended, intensive listening.

None of this is surprising, given the price differences. Simaudio’s Moon 390 is a full-fledged streaming DAC–preamp, but it retails for $6400. The price for the Chord Qutest was recently reduced from $2125 to $1595. Even at the new price, the Qutest costs 23% more than the Diablo 2, and it lacks a headphone amp.

The Diablo 2’s virtues as a headphone amplifier were immediately obvious. It drove my demanding Audeze ’phones with blissful ease, handily outclassing the headphone amp in my Moon 390. And the iDSD Diablo 2 punched way above its weight and price class when used as a source component in a two-channel setup for out-loud listening.

. . . Killain Jones
killain@soundstage.com

Associated Equipment

• Loudspeakers: Klipsch Forte III.
• Headphones: Audeze LCD-2 Closed-Back.
• Streaming DAC–preamplifier: Simaudio Moon 390.
• Power amplifier: Simaudio Moon 760A.
• Server: Innuos Zen Mk3 Music Server 1TB.
• DAC: Chord Electronics Qutest.
• Cables: AudioQuest Coffee USB link, Kimber Kable Select KS 1116 balanced interconnect, Shunyata Research Venom RCA interconnect, Youkamoo 4.4mm-to-dual-XLR male balanced interconnect.
• Speaker cables: Kimber Kable Ascent TC series 8TC.
• Mobile devices: Apple iPad, Apple iPhone 13 Pro.
• Power conditioner: AudioQuest Niagara 1200.
• Power cords: AudioQuest Storm Series Thunder power cable (for conditioner), Shunyata Research Venom NR V12 (for preamplifier), Shunyata Research NR V10 (for power amplifier), Shunyata Research Venom V14 (for music server).

iFi Audio iDSD Diablo 2 DAC–Headphone Amplifier
Price: $1299.
Warranty: One year, parts and labor.

iFi Audio
79 Scarisbrick New Road
Southport, PR8 6LJ
England, UK
Phone: +44 (0)1704 543 858

Website: www.ifi-audio.com

US distributor:
iFi Audio USA
1211 Park Ave, Suite 102
San Jose, CA 95126
Phone: 1-800-799-4342

Website: www.ifi-audio.com

Canadian distributor:
Erikson Consumer—An Exertis | JAM business
Baie-D’Urfé, Quebec H9X 4B7
Phone: 1-800-567-3275

Website: www.eriksonconsumer.com