Review: iFi Audio iDSD Pro 4.4mm

The iFi Audio iDSD Pro DAC is an ultra-versatile audiophile model that can be used as a USB DAC, a headphone amplifier and a network streamer. It is DLNA and AirPlay compatible and can access many online music services such as Tidal, Spotify, Qobuz, etc. Certified Hi-Res Audio, it uses four Burr Brown DACs to precisely convert PCM streams up to 32-bit/768kHz and DSD streams up to 49MHz. There are two versions of this device: the first features a 2.5mm balanced headphone output (iFi Audio iDSD Pro 2.5mm) and the second is equipped with a 4.4mm balanced output (iFi Audio iDSD Pro 4.4mm). This review concerns the second version. Sold for €2.999, will this DAC, which has received numerous awards from the international press, be able to get the most out of all our dematerialized music? Find out in this review.

iFi Audio iDSD Pro: the brand

iFi Audio’s story began in 2012 when the English manufacturer AMR (Abbingdon Music Research), which had previously specialized in amplifier, CD player and speaker design, decided to establish a new subsidiary dedicated to portable systems and dematerialized music. Right from the start, iFi Audio was therefore able to benefit from all the expertise of its parent company to provide innovative systems, combining the best audiophile components with the latest technologies. A decision that has paid off, as iFi Audio has made a name for itself in the world of hi-fi and has been unanimously acclaimed by the international press.

Today, iFi Audio’s catalog includes portable headphone amplifiers, power conditioners, portable audio DACs, hi-fi preamplifiers and phono preamplifiers. All these devices feature high-quality components and are built to last as long as possible. These characteristics can be found in the iFi Audio iDSD Pro DAC, which combines all of the brand’s best technologies and components to bring digital music to life.

iFi Audio iDSD Pro: packaging and accessories

The iFi Audio iDSD Pro DAC and headphone amp comes in a cardboard box and is protected by thick pieces of packing foam. It comes with a quick start guide, an RCA cable, a USB-A to USB-B cable, a power adapter and a remote control. The latter isn’t really suitable for a high-end DAC. Very small, it is made of rather flimsy plastic and is crudely assembled. Moreover, it requires a CR2025 battery which isn’t included. The remote control isn’t very user-friendly and can only control the volume. Consequently, turning the DAC on, selecting the source, selecting the operating mode or carrying out any other command has to be done through the iFi Audio iDSD Pro’s interface. Lastly, the iDSD Pro DAC also comes with a WiFi antenna. Once more, we would have liked the British manufacturer to have taken more care with its design. It is made from white plastic and disrupts the high-end look of the device. Thankfully, this antenna can be folded behind the DAC or taken off when using an Ethernet connection.

iFi Audio iDSD Pro: presentation

The iFi Audio iDSD Pro streamer features an elegant chassis in solid brushed aluminum. The latter is designed to be vibration-resistant and rests on a large rubber base. For even more effective decoupling, we placed the streamer on the iFi Audio iRACK Pro stand, which features a tube-shaped structure in stainless steel and feet with a marble center to reduce vibration to a minimum.

On the front panel, the iFi Audio iDSD Pro DAC features a circular OLED screen that displays the selected source and sample rate of the file being played (with and without upscaling). To the left of the screen, the iFi Audio iDSD Pro 4.4mm network streamer integrates an on/off button, as well as a large knob to select the source. The latter can also be used to adjust the brightness of the display with a short press, and invert polarity with a long press. A second, smaller knob lets you select one of the digital filters, activate Bit Perfect playback or carry out upsampling. Underneath is a switch with three positions to quickly change the headphone amp or the preamplifier’s operating mode: Transistor, Tube and Tube+.

To the right of its OLED display, the iFi Audio iDSD Pro 4.4mm DAC features a large motorized knob that lets you adjust the volume of the three headphone outputs: an unbalanced 6.5mm jack output, balanced 4.4mm mini-jack (Pentaconn) output and unbalanced 3.5mm mini-jack output. The latter can drive unbalanced or balanced headphones thanks to a special four-pin design. We will go into more detail on how this mini-jack output works later in this review.

Other than the headphone outputs, the iFi Audio iDSD Pro DAC’s connectors are all on the rear panel of the device. There is a USB-A input to play music from a USB flash drive or an external hard drive, a coaxial input, a digital XLR input, a USB-B input to use the device as a USB DAC with a computer, a micro SD port, an Ethernet port and a WiFi antenna to connect to the network. A BNC port is also available to pair the iFi Audio iDSD DAC with an external synchronization clock. The latter can be either a DARS (Digital Audio Reference Signal) or an atomic model, or set to a frequency of 10MHz. There is also a synchronization signal output for chaining with other devices.

To ensure it is perfectly compatible with any amplifier, the iFi Audio iDSD Pro DAC includes an unbalanced RCA stereo output and a balanced XLR output. Four output modes are available: HiFi Fixed, HiFi Variable, Pro Fixed and Pro Variable. These different modes mainly affect the signal output level. The iFi Audio iDSD Pro DAC can therefore be used as just a source or as a pre-amplifier. The maximum output level is 10V for the XLR outputs and 5V for the RCA outputs in Pro Variable mode.

iFi Audio iDSD Pro: quadruple DAC

The iFi Audio iDSD Pro is designed to perfectly handle the vast majority of audio formats up to 32-bits/768kHz, as well as MQA, DXD and DSD files up to 49MHz (DSD1024). To precisely decode such a large amount of data, the iFi Audio iDSD Pro uses a total of four Burr-Brown DSD1793 DACs mounted in an interleaved configuration. This layout avoids any phase correlation and improves the signal-to-noise ratio by + 6dB. The iDSD Pro’s different DACs are paired with a femto GMT (Global Master Timing) precision clock to reduce jitter to a minimum. Jitter is also reduced thanks to the incorporation of an XMOS XU216 X-Core 200 16-core processor.

iFi Audio iDSD Pro: filters and DSD upsampling

To suit each user’s preferences and equipment, the iFi Audio iDSD Pro DAC and headphone amplifier features several digital filters: 

• Gibbs Transient Optimised: minimum filtering, no pre-ringing, minimum post-ringing. 768kHz upsampling  
• Apodizing: modest filtering, no pre-ringing, modest post-ringing. 768kHz upsampling  
• Transient Aligned: maximum filtering, maximum pre-ringing, maximum post-ringing. 768kHz upsampling

Naturally, the digital filters can be bypassed by activating the Bit Perfect or Bit Perfect+ modes. The latter bypasses any filtering and improves synchronization. Lastly, the iFi Audio iDSD Pro also includes a Studio DSD Remastering system specifically designed to upscale PCM streams to DSD. It is possible to select DSD 22.5 MHz or DSD 45 MHz encoding. This “remastering” is very interesting, especially with compressed files as we will see later on in our review.

iFi Audio iDSD Pro: solid-state or tube amplification

The iFi Audio iDSD Pro’s amplification section has three different operating modes: Solid-state, Tube and Tube+. In Solid-state mode, the iFi Audio Pro uses a Class A quad amplifier with iFi Audio J-Fet OV4627A inputs. In Tube mode, amplification is assigned to a pair of General Electric GE5760 tubes. Finally, the Tube+ mode still uses the General Electric tubes, but reduces negative feedback to a minimum to reduce harmonic distortion. These different modes can be easily selected using the three-position switch on the iFi Audio iDSD pro’s front panel. Conveniently, the color of the iFi Audio logo’s backlight changes depending on the chosen mode. It is white in Solid-state mode, it flashes white when the tubes are warming up, and is yellow in the Tube and Tube+ modes.

iFi Audio iDSD Pro: headphone amplifier

Designed to drive all headphones and earphones in the market, the iFi Audio iDSD Pro provides three types of headphone outputs. There is an unbalanced 6.35mm jack output, a balanced 4.4mm balanced mini-jack output and an unbalanced 3.5mm SE output. The latter has the particularity of featuring four contact points. Consequently, it can be used to drive both unbalanced and balanced headphones. The iFi Audio iDSD Pro headphone amplifier’s output power at 16 ohms is 1575mW with the unbalanced output and 4200mW with the balanced output. A three-position switch lets you easily adjust the amplification gain: 0dB, +9dB and +18dB. In other words, this amplifier can drive any headphones.

iFi Audio iDSD Pro: DLNA, AirPlay and streaming

Thanks to its dual WiFi and Ethernet network controller, the iFi Audio iDSD Pro DAC can be easily added to a network and connected to the internet. It is then possible to play music shared using DLNA on the local network, but also to access numerous online music services such as Tidal, Spotify and Qobuz. These services can be controlled on the free Müzo Player app for iOS and Android. This app allows WiFi streaming up to 24-bit/192kHz. Lastly, the iFi Audio iDSD Pro network streamer is compatible with the Apple AirPlay protocol to effortlessly stream music from an iPhone, iPod or Mac.

iFi Audio iDSD Pro: configuration

For our review of the iFi Audio iDSD Pro, we placed it on the iFi Audio iRACK Pro stand to eliminate all unwanted vibration and optimize the chassis’ heat dispersion. The iFi Audio iDSD Pro streamer can be set up in a few simple steps. After connecting the different sources, it must be connected to the network via WiFi or Ethernet to benefit from the many network features. To begin WiFi pairing, simply press and hold the DAC’s WPS potentiometer for a few seconds, then join the WiFi network named “iFi Audio iDSD Pro” on your smartphone or tablet. The rest of the procedure is carried out in the free Müzo Player app for iOS and Android. In this app, you must select the device you wish to configure and enter the local WiFi password for the iDSD Pro DAC to be automatically connected. You can then play music shared over the local network and access different online music services in the same app.

iFi Audio iDSD Pro: listening impressions

Headphone amplifier, Solid-state mode

First, we tested the iFi Audio iDSD Pro’s headphone amplifier by pairing it with the Audeze LCD-4z headphones. This over-ear open-back model has an impedance of 15 ohms, a sensitivity rating of 98 dB and a recommended power level of 250W. Connected to the iFi Audio iDSD Pro’s unbalanced 6.5mm jack and balanced 4.4mm outputs, it was effortlessly driven with the gain selector set to 0dB. With the Dire Straits’ Sultans of Swing in 24-bit/88kHz, the iFi Audio iDSD Pro was incredibly dynamic. The soundstage was wide and each tiny detail was perfectly reproduced. The voices were centered and it was almost as if the band was on stage in front of us.

Headphone amplifier, Tube and Tube+ modes

Still using the Audeze LCD-4z, we then tested the tube amplification. Activating this mode requires a very brief warm-up period. Once operational, some vitality was lost and the lows weren’t quite as deep as they were with the Solid-state mode. However, the music was warmer, especially with jazz tracks. On the track The Girl From Ipanema by Stan Getz & João Gilberto in 24-bit/192kHz, the sound was smooth and very serene. The many details in this song were perfectly reproduced and excellently positioned. The soundstage was wide and tall, allowing the saxophone to be expressed with great ease. We could even hear Stan Getz’s breath. The voices of João Gilberto and Astrud Gilberto were smooth, tuneful, textured and more natural-sounding than ever before. These characteristics were also present with the Tube+ mode. The latter managed the feat of bringing even more precision to the smallest details. The soundstage was slightly wider. The sound was incredibly serene, inviting us to turn the volume up and listen to track after track. 

Line output and preamplification

We then tested the iFi Audio iDSD Pro’s performance as a source by pairing it with a McIntosh MA352 hybrid amplifier using Viard Audio Design Premium HD RCA cables. We used the Elipson Legacy 3230 speakers. With the hi-fi line output, the iFi Audio iDSD Pro DAC harnessed the full potential of the McIntosh amp. Together, they formed an ideal pair. The soundstage was extensive, the frequencies were balanced and the lows were very deep, no matter the style of music. We provide more details about this combination in our review of the Mcintosh MA352. 

The iFi Audio iDSD Pro streamer’s analog outputs can easily be switched to fixed or variable mode using a switch on the back of the DAC. As a result, it is possible to use this iFi Audio DAC as a solid-state or tube hi-fi preamplifier. To test this feature, we connected it to the By-Pass input of the Atoll IN200 amplifier and selected the “Variable hi-fi” mode on the DAC. We continued to use the Elipson Legacy 3230 speakers. The iFi Audio iDSD Pro network streamer was exceptional as a preamplifier in this setup. The volume was adjusted very easily and smoothly. In Tube+ mode, we rediscovered the warm and soft sound signature that had already captivated us during our previous listening sessions using headphones. Even with compressed music streamed from Spotify (maximum bitrate: 320 kbits), the iFi Audio iDSD Pro streamer worked wonders. With these compressed files, the various digital filters and the DSD 45MHz upscaling provided a significant improvement, especially in the highs, which were smoother and more natural. The sound was never aggressive and we enjoyed switching between the DAC’s different modes.

iFi Audio iDSD Pro: compared to…

iFi Audio iDSD Pro 2.5mm: the iDSD Pro 2.5mm could be described as the iDSD Pro 4.4mm’s twin and is only different in two ways. Firstly, it uses a balanced 2.5mm headphone output instead of the 4.4mm format. Secondly, the output power of the iDSD Pro 2.5mm’s headphone outputs is slightly lower: at 16 ohms, 4000mW for the balanced output and 1500mW for the unbalanced output. Other than that, both devices are identical, with the same components, the same 32-bit/768kHz and DSD 49MHz compatibility, and the same network features. Consequently, choosing between these two models is mainly a matter of compatibility with the headphones or earphones you wish to power.

iFi Audio iDSD Pro: conclusion 

With the iFi Audio iDSD Pro DAC, the British manufacturer provides an ultra-effective and very comprehensive solution that can be used as a USB DAC, a network streamer, a hi-fi preamplifier and a headphone amplifier. We tested all of these modes and iFi Audio iDSD Pro excelled every single time. Its multiple DACs always knew how to breathe life into dematerialized music, even compressed tracks. The headphone amp proved to be extremely precise and worthy of the best analog electronics. Its high output power allows it to effortlessly drive any pair of hi-fi headphones or earphones. The amplifier’s different operating modes provide an excellent solution to adjust the restitution to suit your preferences or the music you are listening to. The Solid-state mode is very dynamic and perfectly suited to classical music, rock and electronic music, while the Tube+ mode is softer and warmer, making it ideal for jazz or bossa nova.

What we liked:

• The Solid-state and Tube+ modes
• The precise decoding
• The versatility of the headphone amplifier
• The very original design

What we would have liked:

• For the WiFi antenna to have been more discreet
• For the remote control to have been more elegant and exhaustive
• A battery for the remote control