StormAudio ISR Fusion 20 Immersive Sound Receiver Review

Posted on 27th June, 2024

StormAudio ISR Fusion 20 Immersive Sound Receiver Review

Tony O'Brien auditions this high-end French AV receiver…


ISR Fusion 20 Immersive Sound Receiver

£19,999 RRP

Storm Audio's ISP.32 and Core 16 Immersive Sound Processors and PA8 Ultra Mk2 power amplifiers have earned numerous accolades worldwide. Yet the French manufacturer has been largely quiet on the subject of AV receivers. That all changed in late 2022, though, when Storm announced the introduction of the ISR Fusion 20 Immersive Sound Receiver at CEDIA.

Like Storm's processors, this seeks to bring cinema-level performance to the home, albeit as a one-box solution. Based on the ISP Core 16 processor, it incorporates 20 channels of processing and 16 channels of inbuilt amplification. Unlike the company's PA8 and PA16 power amplifiers, which use Pascal Class D UMAC modules, the Fusion uses amplification technology from Danish company ICEpower. Of course, getting all of that necessary power into a one-box solution presented its challenges, as Storm's Sébastian Gailleton told me:

With the ICEpower design, we have changed to one power supply driving all the channels, so at any given time, any channel can benefit from full power. This said, the next challenge was of course the space and how to ensure a cool design. Thanks to the compactness of the ICEpower solution, we could embed 16 channels and one power supply with three big quiet fans that are actively controlled to ensure the inside temperature remains within expectations. These fans are from the be quiet! brand, so even at their maximum flow you hardly hear them. This was another challenge to address compared to our former receiver and PAs, which were mostly designed for rack mounts where noise was not an issue. The Fusion is a very busy but cool 4RU unit that you can put in your lounge and forget about.

Respected for their low noise and distortion, the ICEpower modules are backed by a 2,000-watt PSU. Each of the Fusion's 16 amplifiers is rated at 150W, with all channels driven into 8 ohms and up to 500W into 8 ohms when bridged. Like the ISP Core 16, the Fusion 20 is equipped with two ADI Sharc DSP4 processors. Decoupling the input and output DSPs is claimed to yield the lowest possible jitter and provide the cleanest signal path, allowing a greater level of subtlety and detail in the sound.

Sébastian adds: “To us, neutrality is key. We are here to reveal the soundtracks, not to shape them to a specific sound aesthetic – which can be done via the Dirac tool with the target curve adjustment.” 

The Fusion shares the same DAC board as the ISP Core 16, which is claimed to lower residual noise and provide a high dynamic range of 118dB. It's also equipped with Storm's proprietary hybrid analogue/digital volume adjustment, which maximises dynamic range regardless of volume level. It supports the latest audio formats, including Dolby Atmos, DTS:X Pro, Auro (V2), IMAX Enhanced, plus legacy codecs up to 192kHz and is Roon Ready. It can also support any number of subwoofers and drive up to four-way active crossovers. 

Manual calibration includes 20 points of PEQ per channel with REW or Room EQ Wizard. It also includes Storm's Expert Bass Management, providing up to six independent bass zones. These allow subwoofers to be matched to groups of speakers. For instance, bass and LFE from the LCR channels can be routed to subwoofers in the front of the room, with bass and LFE from the side speakers directed to subwoofers on the matching sides of the room, and so on.

Automated calibration is included courtesy of Dirac Live Bass Control (DLBC) and Dirac Live Active Room Treatment (DLART). DLART utilises the system's speakers and subwoofers to actively eliminate bass resonances by an estimated eighty percent in most systems. The results are claimed to provide tighter, more impactful bass that wouldn't otherwise be possible without a well-engineered or treated room.

On the video front, the Fusion's HDMI inputs and outputs support HDMI2.1a/HDCP2.3 up to 8K/4K120 (40Gbps all ports) with HDR10+, HLG and Dolby Vision as well as ARC/eARC. Like other Storm products, its HDMI boards can be upgraded as new formats emerge, as can its DACs and decoding section.


Save for an edgy, angular gloss black façade inset on the black brushed aluminium faceplate, Storm's ISR Fusion 20 Immersive Sound Receiver is otherwise identical to the ISP Core 16. It's a small change but a welcome progression, each successive model a little more refined and sophisticated in its styling. You'll find little in the way of controls, save for a volume knob and three small buttons for menu navigation. Like many of today's sophisticated AV processors and receivers, it's far simpler to navigate the setup menu via the web GUI.

At 491x174x442mm (without feet), the Fusion is similar in size to most flagship receivers and weighs in at a solid 16kg. Bearing this in mind, it shouldn't represent much of a challenge in terms of placement. And for those with racks, it utilises just 3RU. A fraction of the space of a dedicated processor and a rack of amplifiers.

Move to the back of the Fusion, and you'll find the same brushed silver finish found on all Storm products. Like the front panel, it's obviously been lovingly crafted. Its gold-plated, five-way speaker posts not only look like the business but are extremely solid. There are seven HDMI inputs and two HDMI outputs. Other digital connections consist of three optical TOSLINK inputs, three coaxial inputs, one TOSLINK output (Zone 2 stereo downmix) and three USB inputs. Analogue connections consist of four RCA inputs (7.1 or stereo), one XLR stereo input, and four-channel XLR analogue XLR outputs. Control options include two 12v inputs and outputs, a single IR input and output, and a LAN input.

The box includes rack ears, a power cord, a manual and a remote control. Although the remote has improved over previous generations, it still feels like an afterthought and is a far cry from the more feature-laden remotes of mainstream offerings. In all fairness, though, control of the Fusion is more likely to be handled by a third-party remote control such as Control4, Crestron, RTI, Savant or ELAN, all of which it is compatible with.


Although it's not entirely self-explanatory, setting up the Fusion 20 is fairly straightforward after familiarising yourself with the manual. However, if reading a user manual is enough to put you to sleep, you'll find a wealth of simple-to-follow tutorials on Storm's YouTube channel.

Using the web GUI, it's a relatively straightforward matter of assigning speaker channels – all of Fusion's 16 channels are assignable – and creating your first theatre. The GUI provides clear diagrams and 3D speaker views of the bed, height, and overhead speaker layers. And should the preset configurations not meet your needs, you can simply add or delete speakers. You can also create multiple theatres and sub-theatres, the latter of which allows a subset of speakers within an existing theatre to be used.

Dirac is a powerful calibration tool, and I imagine most will rightly use it, given the inclusion of a Dirac Live Active Room Treatment (DLART) license with the purchase of the Fusion. Although it's an automated calibration tool, it does require an external microphone and a learning curve to get the best results. And, if you plan on using DLART – which is highly recommended – then knowledge of your speakers' capabilities is a must. If all this sounds a little daunting, your dealer will most likely arrange it for you during installation. 

For this review, the receiver was connected to VAF Signature i91 front and centre speakers, with six VAF i90s used as rear surround and ceiling-mounted Atmos speakers, with two Ascendo The 16 SUB subwoofers to create a 5.2.4 Atmos layout. Video sources comprised of a Magnetar UDP-900 4K Blu-ray player and Apple TV, connected directly to a Lumagen Radiance Pro 5348, with images projected directly onto a Severtson 100” Cinegray 16.9 screen with a Sony VPL-XW5000ES projector.


Storm Audio's ISR Fusion 20 Immersive Sound Receiver delivers a very cinematic performance. Dynamics are delivered both cleanly and powerfully, with this big receiver deathly quiet one moment, then serving up heart-racing dynamics the next.

Bass performance is superb; the silky smooth bottom end has a level of tonality, tightness and impact that is simply not possible without a well-treated and engineered room. As big and cinematic as it is however, it exhibits wonderful transparency and fine detail that is able to extract the subtlest of nuances from soundtracks.

One of the latest to get the 4K treatment is John Woo's 1990s action flick Face Off. Despite being limited to a DTS-HD Master soundtrack, there are still plenty of thrills and spills to be had. With the edgy soundtrack and accompanying mayhem, the Fusion delivers a punchy performance. The marriage of DLART and powerful amplifiers makes for lightning-fast dynamics.

While my subs are excellent performers in their own right, DLART makes me realise just how much I had been missing due to the room. Bass is silky smooth with increased tonality and atmosphere. Whether it's the distinctive backing track, gunshots or simply the sound of footfalls, DLART adds an extra layer of information that is otherwise simply not there.

It accomplishes this with the sonic force of a freight train, with gunshots and explosions clearly felt and heard at the listening position. While I've been aware of the benefits of DLART for some time, I've never experienced it in my room. Unless you have a well-engineered and treated home cinema, you've never heard bass like this before.

Meanwhile, those ICEpower amplifier modules fill my room with loud cinema-like sound. Capable of reaching massive volume levels, it's cinema at home rather than home cinema. If I hadn't known better, I would have thought I was listening to a very high-end pre/power combination rather than an AV receiver.

Moving to 2017's Life on 4K Blu-ray, the ISR Fusion put in a blistering performance with the reference-grade Dolby Atmos soundtrack. As the ship hurtles through space, the Fusion creates a massive sound field that's as big and bold as it is powerful. 

It's not just the big things that the Fusion excels with. Like Storm's dedicated processors, this receiver exhibits a wonderful transparency and sense of detail. As the crew go about their functions, the flicking of switches can be made out on the left-hand side of the room, while dialogue's centred on the middle speaker. It's much the same with the odd rattle of the structure of the ship. While detail retrieval should be a staple of any high-end AV receiver, it's both the transparency and clarity with which the Fusion presents it that makes you feel as though the sound is coming from the room itself rather than the speakers.

It's much the same with the Dolby Atmos Soundtrack that accompanies the 4K Blu-ray of Bullet Train. Here, the Fusion's transparency enables viewers to absorb all the detail, from the swishing of doors to the clarity of the dialogue, which never gets lost during the film's more chaotic moments. With such a loud and explosive combo, I couldn't resist the opportunity to test the Fusion with the 4K Blu-ray of Ready Player One. Once again, it revealed an impressive amount of detail in everything, from the subtle yet impactful bass of the Sixers arriving through a portal to the GUI that Parcival conjures of his fuel tank.

As the race begins, every bump and smash is felt clearly at the listening position with loud and dynamic sound that's nothing short of spectacular. The Fusion conjures all the mayhem of the race, with the sound of smashing metal and explosions going off all around the soundfield. Kong's appearance is no less impressive, the noise of his footfalls smashing through my listening room.


Make no mistake – Storm's ISR Fusion 20 Immersive Sound Receiver is very expensive. At two to three times the cost of competing flagship receivers, it's a stretch. While that may be the case, the Fusion is anything but a receiver, with performance more akin to serious high-end separates. Simply put, sonically, it runs rings around other AV receivers.

Its outstanding power reserves and dynamic kick-in-the-pants performance make for a truly exhilarating listen. Coupled with its transparency and detail, it delivers a true cinema-at-home performance. If you're looking for dynamic, cinema-like sound levels and excitement in the comfort of your home, then this is an essential audition.

For more information visit StormAudio

    Tony O'Brien's avatar

    Tony O'Brien

    Tony is a certified ISF Calibrator by day, and an accomplished Audio-Visual reviewer specialising in theatre and visual products by night. Tony has calibrated and worked with some of the best home cinema designers throughout Australia.

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