iFi Audio's Pro iDSD: Streamer, DAC, Headphone Amp, Preamp -- All in One!

March 2019

SoundStage! has covered multiple products from iFi Audio. We began by looking at their earlier, value-centered products, many of which were involved with some aspect of headphone listening. In the last few years, iFi seems to have decided that the high end offers a promising marketplace as well. Their Pro iDSD ($2499 USD) now joins their Pro iCAN headphone amp ($1799) and Pro iESL electrostatic headphone amplifier ($1499) -- attempts to challenge the Mount Everest of the highest-quality audio products while maintaining at least a semblance of reasonable pricing.

In audio, we have everything from the plain and easy to the serpentinely elaborate. You have to look in the mirror and determine whether you’re a member of the straight-wire-with-gain clique, or if you think today’s fully loaded A/V receivers could still include a few more tricks.

The iFi Pro iDSD streamer-DAC-headphone amp-preamp ($2499) falls most defiantly on the complex-is-good side. It plays DSD or PCM signals through its solid-state J-FET driver or a pair of GE 5670 tubes, and it offers multiple choices of inputs, outputs, filters, and frequency responses. For Tidal listeners, it even handles MQA. It’s so complicated that you can end up suffering delusions of inadequacy similar to those that strike old tube-amp aficionados, who constantly worry about the age of their tubes and the accuracy of their bias settings -- or tweakers who spend hundreds of dollars for little doohickeys that raise speaker cables off the floor but can’t decide which way sounds better.

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One thing you won’t have to wonder about with the iDSD is whether or not iFi uses high-quality parts. I could spend this entire article drooling over the iDSD’s various components. Unless you’re a particularly knowledgeable electrical engineer, the specifics might make you go cross-eyed.

Here are two examples: First, the Pro iDSD contains an expensive rotary Japan Alps motorized volume potentiometer. iFi uses the six-track version, so that they can devote four tracks to ensuring balanced operation throughout the entire piece of gear. It would have been cheaper to use a digital volume control buried somewhere in the chipset, but iFi’s engineers felt that the iDSD sounded better with the Alps. Second, their Crysopeia FPGA Digital Engine can upsample all music to DSD1024. For those of you who believe that upsampling improves the sound, this is your holy grail: Whether you feed it a PCM or a DSD signal, the iDSD can upsample that signal to a resolution far higher than most DACs are capable of.

If you want to know more about the iDSD’s parts quality, look at their website, which has an enormous wealth of information. Suffice it to say that they’ve invested substantial amounts of time and money in this device. It’s so over-engineered that its price seems a bargain.

If you’re wondering where all this technology came from: iFi is owned by the same folks who make AMR Audio products, such as the positively reviewed DP-777 digital processor, the daddy to the iDSD’s technological palette.

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The iDSD is as close to a genuine all-in-one box as we’re likely to see for a while. It includes a DAC, a preamp, a streamer, and a headphone amplifier. I’d greet this all with a mere ho-hum if any of them felt just tacked on, but there’s a true design gestalt at work here. However, given all that the iDSD can do, and the fact that iFi has implemented it all so carefully and with such a strong core design principle, I should have spent more time with the manual.

I’m an old pro at this stuff. Who needs an owner’s manual? I connected the Pro iDSD to my system and turned it on.

I decided to listen to the Doors’ “Break On Through” (MQA, Elektra/Tidal Masters), and suddenly I found out exactly how loud my Barefoot Sound speakers will go -- way into the hearing-damaging zone. Ouch. Remember those ads for Maxell audio tape, with the guy sitting in front of his speakers and his long hair blown back straight behind him?

What happened? The iDSD had ceded control of the volume to the Mac computer, something I’ve never experienced with other audio interfaces. I read the manual a little more closely. From p.8: “Warning: at the outset do not use excessive gain, otherwise damage to hearing or connected headphones may ensue. AMR/iFi Audio is not responsible for any damage/injury from misuse.” (iFi’s italics)

What did they say? Couldn’t hear ’em. Anyway, I’m sure you’ll be smarter than I was. Read the manual.

Most of the iDSD’s manual is online, and it was clearly written by a native and literate speaker of English -- there’s lots of wisecracking and ironic humor, sometimes at the expense of useful instruction. There’s a good selection of descriptions of what various things do, but very little about how to make it all work. For now, the best source of information about the Pro iDSD is ifi-audio.com/tech-notes.

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The small Output Mode knob on the Pro iDSD’s rear panel gives you four choices: Pro (Var), Pro (Fixed), HiFi (Var), and the default setting, HiFi (Fixed). Since I planned to use the iDSD as a fully functioning preamp, I switched it to Pro (Var). If you bypass the iDSD’s preamp stage and use it as a DAC, you will want to use one of the (Fixed) outputs.

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The iDSD’s multiple choices of filter and output should make it appeal to professional musicians, as well as to home hi-fi audionauts who like to experiment with the sounds of different filters. iFi has taken great pains to ensure that any change in the signal is in the service of the music. The iDSD’s range of choices offer alterations from the obvious to the extremely subtle.

The first choice is of whether to play the signal as is or to “remaster” it to a DSD512 or DSD1024. Then you have to select a filter: Bitperfect (44.1-192kHz, “always used for 385.2-768kHz”), Bitperfect+ (44.1-96kHz), Gibbs Transient Optimised (44.1-384kHz), Apodising (44.1-384kHz), or Transient Aligned (44.1-384kHz). Finally, you choose the output stage: Solid State, Tube, or Tube+. The Solid State section comprises class-A J-FETs and is clean as a whistle. Tube has an all-tube class-A topology based on GE 5670 tubes. Tube+ reduces the negative feedback to achieve an even more pronounced tube character. I forgot my training in statistics years ago and so can’t tell you how many different combinations are possible among all these options, but it’s a lot. I spent a good deal of time trying the various filters with different types of music, and came up with a hierarchy of what sounded best to me.

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You can also stream music from the Pro iDSD to your system wirelessly or via a direct Ethernet connection. While the wireless function worked flawlessly in my loft condo, I can’t predict how well it would do in a home with lots of walls and square footage. But the only reason to use Wi-Fi when you can hardwire is if you intend to use the iDSD away from a wired connection and as a standalone player streaming music from Spotify, Tidal, Qobuz, or any of the other services the iDSD supports right out of the box.

I tried Spotify, Tidal, YouTube, iTunes, and every other streaming service I could think of, as well as a huge collection of FLACs ripped from what used to be a huge collection of CDs. I began my odyssey with Mark Elder and the Hallé Orchestra’s monumental recording of Arnold Bax’s Tintagel (16-bit/44.1kHz, Hallé/Tidal). I used to play this piece regularly on my evening classical-music radio show (WRR-FM, Dallas), and every time I did, I got phone calls asking what it was. The depth of field and heft of sound were coherent enough that, very shortly after starting it, I forgot about the equipment. The harp glissandi at 3:09 caught my attention for the first time in decades of listening to this work. The sound was delicate, and now that I know that it’s there, I hear it on other recordings, too. This sort of quality of sound is what got me interested in home audio in the first place.

One of the guiltiest of my early guilty pleasures was the Carpenters. Walking out of a record store with albums by Throbbing Gristle, the Stooges, Tangerine Dream, and . . . the Carpenters? “It’s for my Mom,” I said. That seemed to work. Still, Tony Peluso’s stunning guitar solo in “Goodbye to Love,” from the Carpenters’ Singles 1969-1981, is one of my favorite short solos ever, right up there with Elliot Easton’s in the Cars’ “Just What I Needed,” and Eric Clapton’s in Cream’s “We’re Going Wrong.” Tidal has “Goodbye to Love” in MQA, and Peluso’s guitar sound just exploded from the soundstage with all the sparkle I could hope for. Using the iDSD’s Tube+ output along with DSD1024 upsampling yielded a sound guaranteed to soothe the soul of any hard rocker who’s open to different styles of music.

We recently attended a concert by the composer and multi-instrumentalist Ólafur Arnalds, who performed with a string quartet and a percussionist. They played most of his new album, re:member (MQA, Mercury/Tidal Masters), and while it lacks much depth of field, the instruments are recorded beautifully. Arnalds is, in my opinion, an important voice in contemporary classical music. Check out “inconsist” on this album for a nice sample of his work. The iDSD captures the delicacy of Arnalds’s sound, and while a recording always lacks the thrill of a live event, I found the sound of re:member through the iDSD even more seductive than the live sound at the auditorium.

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Max Richter is another young classical composer who’s gaining increasing notoriety. His best-selling recording to date is Vivaldi’s The Four Seasons as Recomposed by Max Richter (MQA, Deutsche Grammophon/Tidal Masters). In the opening cut, Spring 0, Vivaldi’s music emerges from a haze of woozy strings that Richter uses to create a bed of postmodernism. This segues into Spring 1, in which Vivaldi’s writing comes to the fore and Richter’s serves as background. The sound is DG’s usual flattened perspective (too many spot mikes), but a side benefit is the most creamy, luscious string sound imaginable from the Konzerthaus Kammerorchester Berlin and violin soloist Daniel Hope. There’s room sound, as in the famous third movement of Summer, but it comes mostly in the form of reverb tails and echo. The Pro iDSD’s Solid State output stage captured everything gorgeously, and Tube+ certainly added a frisson that any fans of single-ended-triode amplifiers should love.

All this complexity can be daunting. The upside is that you can control almost every parameter from the front and rear panels. But you have to know what each button does when you push it, what it does when you hold it down, and what it does when you turn it -- and every button and control does multiple tasks. The Pro iDSD is manna for musicians who love experimenting with subtle differences in sound, especially guitar players who believe that the only real amp is a tube amp. In fact, I can see engineers in small recording and/or mastering studios making room for the iDSD in their racks of goodies. I finally settled on using Pro (Var) with the Bitperfect+ filter and Solid State output, fed signals straight from my Mac via Ethernet.

A few negatives. iFi has made its bones with headphone components, so you’d expect the Pro iDSD to include a wide selection of headphone options, and it does. You can opt for a 2.5mm TRRS balanced jack, or 3.5mm or 6.3mm single-ended jacks. While the iDSD offers excellent headphone sound, remember iFi’s original Pro product, the iCAN -- a highly specialized product aimed squarely at those rapscallions over at Head-Fi and SoundStage! Solo. iFi even makes a dedicated electrostatic headphone amplifier, the iESL. The good news is that the iDSD has all the headphone performance most people will ever want. But if you’re a cans fanatic, you can start with the iDSD to decide whether it provides the kind of quality you need and want. If it doesn’t -- in which case you have very golden ears, hard-to-drive cans, or just like to spend money -- you can add the iCAN or iESL and end up with an incredible-sounding personal audio adventure.

It’s a shame iFi couldn’t have found room for a balanced XLR headphone output. The 2.5mm jack is easily crimped if you yank out the cord too hard. It would make good business sense to drive customers to a second iFi product, like the iCAN, and adding more balanced outputs to the iDSD might have cannibalized sales of the iCAN. The only balanced headphones I own are the Oppo PM-1s, and I love their sound, comfort, and value. Unfortunately, without a special XLR-to-2.5mm TRS plug, I can’t get the benefits of using a balanced system.

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Tube lovers should be aware that no one makes 5670 tubes anymore, and they’re getting expensive. iFi believes that they’ve now acquired every large stockpile of 5670s on the planet, and they’ve decided to use them only in their new products. If your 5670s fail before the end of the iDSD’s one-year warranty, iFi will replace them. After that, good luck. As of this writing, 5670s are available from Amazon for about $40 per matched pair. Five years from now, who knows? The iDSD completely shuts down the tubed circuits when the Solid State output stage is selected, which will extend the life of the tubes as long as possible. And if the tubes finally fail and can’t be replaced, you can use the Solid State outputs -- which, anyway, I preferred.

The iDSD comes with a remote-control handset. Apparently, the only thing you can do with it is adjust the volume, but with mine I couldn’t even do that -- it came from the factory without a CR-2025 battery, and I didn’t have one available. The iDSD also needs a clearly written and comprehensive instruction manual, whether printed or online. As it stands, all that info is in bits and pieces all over the Internet. And I’d really like it if the Pro iDSD included room-correction software, which I would find a lot more useful than its 37th possible combination of input, filter, and output.

The bottom line, of course, is this: How did iFi Audio’s Pro iDSD sound, feel, and look? Its sound was crystal clear and seemingly imperturbable. Its range of options is crazy wide. It works equally well as a streamer, preamp, DAC, or headphone amp. If you need only one of those, you might be better off with a dedicated component. But the more of these you need, the bigger a bargain the Pro iDSD is at $2499. And it looks nice.

For someone with limited space, a Pro iDSD and a pair of active or powered speakers -- say, Focal’s Solo6 Be ($2998/pair) or Barefoot Sound’s Footprint 01 ($3750/pair) -- would make a mighty fine-sounding system that need fear no competitors.

. . . Wes Marshall

iFi Audio
Southport, Merseyside
England, UK
Phone: +44 (0)1704-227-204

Website: www.ifi-audio.com

iFi Audio (USA)
105 Professional Parkway, Suite 1506
Yorktown, VA 23693

E-mail: enq@ifi-audio.com