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StormAudio ISP MK2 Measurements & Conclusion


 All measurements were conducted using our Audio Precision APx585 8 Channel HDMI Audio Analyzer following our rigid Amplifier Measurement Test Protocol

Frequency Response & Distortion

ISP MK2 Frequency Response

StormAudio ISP MK2 Frequency Response

The ISP MK2 downconverts all high sample rate input signals to 48kHz similar to what most processors do that employ room correction systems like DIRAC. What is interesting is that the ISP MK2 rolls off at 22kHz instead of 24kHz (1/2 sampling rate) indicating they are doing some additional processing that causes this.

ISP MK2 Bass HF noise 

StormAudio ISP MK2 Frequency Response with Bass Management Engaged

I observed some out of band noise at 30kHz (-70dB) and 50kHz (-55dB) with bass management engaged. Although this is inaudible, it is good housekeeping to clean this up. StormAudio told me this will be addressed with the new DAC design.



StormAudio ISP MK2 SINAD vs Level (Volts) @ 1kHz

In effort to help our readers directly compare measured results on Audioholics and Audiosciencereview.com, I am starting to report SINAD figures which is basically the reciprocal of THD+N. The Storm ISP MK2 has lots of output drive and I was unable to make it clip even at max level with a 0dBFS input. The graph above shows SINAD and THD plotted on the Y-axis vs output drive in volts. We see between 91dB to 97dB depending on which channel is driven vs output. These are good results overall.

ISP MK2 Freq vs Distortion

StormAudio ISP MK2 Frequency Response vs Distortion

Update 12/13/21: A thread at ASR was brought to my attention discussing the above measurement with Amir and based on the comments there, I revisted and updated the text below.

The above sweep shows frequency response vs distortion which is exceedingly low at 0.002% THD+N (or 94dB SINAD). The distortion spikes above 5kHz are mostly due to a measurement anomaly caused by a combination of the down-sampling behavour, anti-aliasing filters and the fact that my measurement is wide bandwidth. It is likely so pronounced due to the high input sampling rate and the StormAudio ISP MK2 downsampling to 48Khz and not having usable output above 22kHz. I didn't see this many spikes when sampling at 48kHz but sadly I didn't save that measurement to replace the one above. It’s also still at 0.05% THD+N at 20kHz so still relatively low. I’d like to see better results here but an improvement may likely NOT be audible in most scenarios for even those audiophiles with the best of hearing. StormAudio has informed me a DAC upgrade is in the works slated for sometime in the near future with a possible higher sampling rate offered too. I will be revisiting these measurements once I get the upgrade module installed.


StormAudio ISP MK2 FFT Distortion @ 8Vrms 

The ISP MK2 maintained good composure when driven up to it output limits as shown in the FFT plot above. We see the 3rd order harmonic is 91dB below the fundamental, which is a very good result indeed.

An interesting observation is I was unable to ever clip the outputs of the ISP MK2 even with a 0dBFS input and the volume set to maximum which is why I wasn’t able to include a distortion vs output sweep like I typically do in our preamp reviews. Suffice it to say, this processor provides a clean 8Vrms via its balanced outputs.

ISP MK2 Square Wave 

StormAudio ISP MK2 Square Wave Response

I ran a 1kHz square wave into the ISP MK2 and found some under and overshoot. Ideally there'd be no overshoot or ringing like we are seeing in the curve above. This is likely due to the steep DAC filter settings StormAudio chose for this product for noise shaping. We don't listen to square waves so don't put too much concern in this result.

Signal to Noise Ratio and Dynamic Range (AES-17)


 ISP MK2 Dynamic Range

 StormAudio ISP MK2 SNR Analog output (Amode)

Note: Ignore channel 4 results as that's the subwoofer channel and this test was done at 1kHz which is out of band.

When I first got the ISP MK2 last year and did a series of measurements, the SNR results were NOT stellar for a product of this caliber. I worked with StormAudio to verify my measurements and as a result they prepared an updated beta firmware to improve the results. Since the ISP MK2 has both analog and digital preamp outputs, you can now select which type you are using for each output to yield the best performance. Configuring the analog outputs with this new optimized setting improved SNR 10dB. This is a very good measurement. The latest software release 4.1r2 contains this fix and you should upgrade if you’re running older firmware. I use both digital and analog outputs in my speaker configuration and they are both dead silent.


StormAudio ISP MK2 CH-CH Crosstalk

The two channels in purple and blue were configured for (A-mode, analog optimization) and ironically have higher CH-CH crosstalk than the other channels optimized for the digital outputs. Regardless, the CH-CH crosstalk with one channel undriven is excellent at -75dB @ 20kHz.

Bass Management

In my 20+ years of writing about audio equipment, I’ve never run across a more comprehensive bass management system than what StormAudio offers with their ISP MK2. I don’t think I will be able to articulate the full extent of its abilities here but will do my best to provide a sense of its power.

Bass MGMT Standard 

StormAudio ISP MK2 Standard Bass Management Mode

In standard mode, you see very similar bass management capabilities found in most AVRs and processors. I tested the typical bass management settings you’d use in a THX environment where the crossovers were set at 80Hz with a 2nd order Butterworth HPF for bass managed speakers and a 4th order Linkwitz-Riley LPF for the subwoofer with a 120Hz LPE for the LFE channel.


StormAudio ISP MK2 Bass Management “Standard” Mode Frequency Response

I observed textbook filter response that would easily earn StormAudio THX approval if they sought the licensing for it. The HPF set for 80Hz (-3dB) measured a slope of 12dB/oct while the subwoofer measured 24dB/oct and -6dB at 80Hz. Bravo!

What separates the Storm ISP MK2 from virtually every other AV processor on the market is its almost infinite capabilities to route bass that is customized for your particular installation. For my setup, I’m running very large true full-range RBH Sound SVTRS Active towers that I wanted to route bass from all channels set to “small” and LFE to them in addition to sending the LFE to a 3rd sub at the back of the room. I was able to accomplish this in the ”expert” bass management setting using “Large and Sub” settings and by creating bass zones for the Left/Right channels and the additional subwoofer.

Expert Bass MGMT 

StormAudio ISP MK2 Expert Bass Management Mode

Using “Large and Sub” allowed me to run my main speakers full-range and also feed them bass from ALL speakers set to “small” plus LFE.  With most processors, you can’t run LFE to the main channels IF you also had a dedicated subwoofer channel. In such instances, the user would have to disable the subwoofer channel to route all bass to the mains. This typically causes overload conditions, which can cause digital clipping or simply too much bass. Is too much bass even possible for a Bassaholic? You betcha. The Storm ISP MK2 allowed me to scale down the bass summation from each channel fed back to the main Left/Right channels and also reduce the bass level from the main channels being fed to the dedicated sub to reduce the risk of overload or too much bass. This type of flexibility is what really helps an end user get great bass integration between their speakers and subs.

The ISP MK2 also has an internal test tone generator to help you calibrate via bandwidth limited or fullrange pink noise or external via REW measurement software. I used the external option so I could sweep each channel individually with the subs engaged to make sure I was getting optimal bass integration and level. While most processors are limited to 0.5dB increments in level and .1ft distance changes for speaker delays, StormAudio allows much finer adjustments. You can literally enter in the settings to the thousandths place. Incredible!

Bass Routing 

StormAudio ISP MK2 Bass Routing

Even when I played back the Dolby Atmos “Amaze” demo, which has the highest LFE bass content I’ve ever seen, I was unable to overload any of my subs either at the preamp level or at the speaker level, thanks to the proper scaling this processor enabled me to achieve.


Bass Management Expert 

StormAudio ISP MK2 Expert Mode Variable Bass Management

As you can see in the above graph, the ISP MK2 allows you to adjust crossover points and slope for each channel group individually. I was able to achieve this while also still having the proper bass summation, and filter slope going to the subwoofer channel.

I caution anyone wanting to run full-range speakers about the “Large with Sub” setting. I studied this and it still doesn’t make total sense to me. This mode does copy the bass from whatever channel group you set this to and sends it to the subs, BUT the actual channel group still gets a HPF applied. If you set your mains to “Large with Sub” it’s essentially similar to setting those speakers to small as you can see in the graph below. 


Bass Large w Sub 

StormAudio ISP MK2 Expert Mode Variable Bass Management “Large with Sub”

If you want your main speakers to be true full-range and want to route the main channel bass to your subs, use the “Large and Sub” option instead.


One would expect a product of this price caliber to have nothing to complain about, but then you wouldn’t be reading Audioholics if you didn’t want to see me whine about something, right? As good as the StormAudio ISP MK2 is, there are things I’d like to see improved upon. One minor strike against this product is it doesn’t currently support HDMI 2.1 which is likely only an issue if you're a gamer playing in 8K. This is to be expected as the bleeding edge with the latest HDMI chips are usually first implemented by the giants in the industry like Denon, Marantz, and Yamaha. They have a multi-tier production line of AV receivers and processors under development with higher purchasing procurement on parts and more resources at their disposal for quicker productization. StormAudio does have an upgrade path to HDMI 2.1 that we will learn more about next year. The Storm ISP MK2 currently doesn’t utilize a SOTA DAC section like you’d expect for a product of this price. While it’s not bad per se, it just doesn’t produce the best-in-class measurements we’d expect. StormAudio has a new DAC board in the works for 2022 that should bring the level of performance that will put a smile on my face when it produces impeccable bench test results. Let me be clear that I did not find the sound quality lacking in any of my listening tests with the current DAC implementation of this product. 

The StormAudio ISP MK2 is NOT without its operational hiccups. For example, I couldn’t play back DTS CD’s through HDMI with the current firmware at the time of this review but StormAudio told me this has been addressed in firmware ver 4.2r1 which I have yet to test. Prior to the firmware fix, the workaround was to connect toslink from my OPPO Blu-ray player to the ISP MK2 and switch to that input on the rare occasion when I still spin those discs. There have been issues where HDMI would lock up and I couldn't restore the picture or sound even with a power cycle. This mostly occurred when my laptop was plugged into the processor via HDMI for doing acoustical measurements with REW. I’ve had rare occasions where the unit would become unresponsive and I’d have to unplug the power to reset it. These are all livable issues to just be aware of, NOT to deter your consideration of integrating this product into your home theater.

Storm Speaker Config

StormAudio ISP MK2 Speaker Configuration Layout Diagram

Last but not least, the biggest Achille’s Heel for the ISP MK2 is by design, one I do not agree with StormAudio about. You are married to a speaker configuration once you set it. If you later decide to add an additional subwoofer channel or a pair of height channels, you must go back and do a completely new speaker configuration. If you plan ahead and add an extra subwoofer channel, DIRAC won’t let you run the calibration with unused channels present. While I can appreciate the reasoning StormAudio imposed this limitation to avoid the end user accidentally changing the speaker configuration, I hope they reconsider and allow pro installers the option of changing speaker configurations for the customer, perhaps in a hidden password protected submenu.

Another potential negative about the StormAudio ISP MK2 is that it doesn't have a analog bypass or phono preamp section. But to put things into prospective, many high end AV processors such as the Trinnov Altitude or Monolith HTP-1 don't either. Every signal that comes into the ISP MK2 must get digitized. This isn't a concern IF you're not spinning vinyl or playing back analog sources. It's possible StormAudio may introduce an analog direct mode in the future but for now, you're gonna have to have a separate analog preamp and phono section if you're a vinyl lover.


Storm Audio ISP MK2 heroThe StormAudio ISP MK2 is a technological marvel for cost-no-object AV processor. I am still in awe at the sophistication of its bass management system that can handle any type of speaker and subwoofer combination you could ever think to conceive. The speaker configurability ranges from modest all the way to SOTA 24-channel native immersive speaker layouts and up to 32 processed channels to build the very best large scale home theaters. The digital outputs allow the end user to integrate the bleeding edge in active speaker technology with a straight digital path to external processing with no analog to digital conversion like you would have with conventional processors.  This is such a big deal that I can’t overstate it. The end result is sonic perfection that enables you to build the system on your dreams rivaling the best cineplexes while also treating music with equal veracity. I like the fact that StormAudio builds this processor with upgradeability in mind (ie. HDMI 2.1, DTS Pro, etc). This ensures obsolescence won’t be an issue the way it is with most AV products that are not modular based like the ISP MK2. As much as I loved experiencing Dolby Atmos movies processed by the ISP MK2, the real treat for me was listening to Atmos music through Apple Music and Tidal. I felt that the ISP MK2 really let me dial in the “audiophile” in my system with all of the infinite adjustability that you just don’t get in a mass produced AV processor. Because of the level of configurability and associated performance I was able to achieve in my theater room, the StormAudio ISP MK2 is our 2021 Product of the Year Award winner in the AV Processor category.  I am looking forward to the future upgrades that will enhance the performance and features of this product and plan to continue on my home theater journey in the AH SmartHome with StormAudio at the helm.

2021 Product of Year

StormAudio ISP MK2

MSRP: $24k (as configured)

Contact StormAudio

The Score Card

The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:

Performance × Price Factor/Value = Rating

Audioholics.com note: The ratings indicated below are based on subjective listening and objective testing of the product in question. The rating scale is based on performance/value ratio. If you notice better performing products in future reviews that have lower numbers in certain areas, be aware that the value factor is most likely the culprit. Other Audioholics reviewers may rate products solely based on performance, and each reviewer has his/her own system for ratings.

Audioholics Rating Scale

  • StarStarStarStarStar — Excellent
  • StarStarStarStar — Very Good
  • StarStarStar — Good
  • StarStar — Fair
  • Star — Poor
Frequency Response LinearityStarStarStarStarStar
Bass ManagementStarStarStarStarStar
Build QualityStarStarStarStarStar
Fit and FinishStarStarStarStar
Ease of SetupStarStarStar
About the author:
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Gene manages this organization, establishes relations with manufacturers and keeps Audioholics a well oiled machine. His goal is to educate about home theater and develop more standards in the industry to eliminate consumer confusion clouded by industry snake oil.

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Recent Forum Posts:

jeffca posts on January 04, 2022 19:33
Damn! Another processor that can't run Dirac at 96K! Very disappointing.
DJ7675 posts on December 30, 2021 10:52
The one feature that doesn’t get talked about much with the Storm is their Storm XT. See full description below… but basically what it does is if a speaker is outside of the supported speaker format, it will use that speaker by combining/matrixing it from the nearby speakers. For example, if you use a VOG speaker which will be active for DTSX Pro, and Auro, it would normally be silent when used for Atmos. However, with StormXT it will be active even with Atmos content. Same goes for speakers like Center Height. Another example is the front wides. Currently with the Storm implementation of Dolby Surround Upmixer, FW speakers were not active. But with StormXT they now are. This is something that Trinnov isn’t doing that I know of and is a very nice feature.

StormXT – Beyond natively decoding a large number of channels, with the multiple formats available on the market and their different recommended speaker placements, it is not uncommon to have silent speakers when playing certain content. While this can be a choice, it can be frustrating not to use all speakers to improve immersivity. StormAudio engineers have been working on this challenge and developed a proprietary engine called StormXT that works hand in hand with existing upmix algorithms to extract relevant audio signals from nearby speakers and redirect them to silent speakers. This new feature will be coming to the ISP platform free of charge in 2021.
Movie2099 posts on December 15, 2021 10:35
panteragstk, post: 1525099, member: 61217
I'm just eager to see what they do to differentiate themselves from the competition. These uber high end products do have some compelling features that sometimes trickle down.
Agreed. DataSat was the go to processor back in the 90's and early 2000's. Majority of movie studios used DataSat and then it trickled into residential home theaters and was thee top processor. Then Trinnov came out mid 2000's and was the new toy on the market and DataSat didn't respond. So now that ATI owns them and have been working on new processors for the last 3+ years. I have a feeling they're seeing what is happening in the market and waiting for some of the tech (hdmi 2.1) to be more stable. Working on their own PQ processing or with Dirac or both, depending on which processor. I truly think once they hit the market they'll have all the bells and whistles and state of the art tech hardware to fully compete against and possibly surpass the current big dogs Trinnov and Storm Audio. At least that's my hope. We need more competition in the high end processor market.
panteragstk posts on December 15, 2021 10:26
Movie2099, post: 1525095, member: 90678
Wait until the new DataSat gets released…….Might surprise a lot of people.

I'm just eager to see what they do to differentiate themselves from the competition. These uber high end products do have some compelling features that sometimes trickle down.
Movie2099 posts on December 15, 2021 09:52
gene, post: 1525063, member: 4348
Yea I should have either omitted that measurement or better prequalified it. It was odd that Storm didn't really comment on it when I submitted my test results to them other than to tell me they are working on a new high performance DAC. I absolutely love the Storm ISP MK2 even if it isn't as mature as the great Trinnov.
Wait until the new DataSat gets released…….Might surprise a lot of people.
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