AES Convention is the preeminent bi-yearly gathering for professional audio research, education, and networking. If your interests include Studio Recording, Live Sound, Networked Audio, Broadcast & Streaming, Music Production, Post Production, Game Audio, Spatial Sound, Audio for AR/VR/XR and Product Development, AES Dublin is the place to be! Whether you are an end user, researcher, educator or student, the convention is the place to Listen, Learn and Connect.

We are giving two lectures:

Thursday March 21
Compact Stereo Loudspeakers with Dipole Processing
Christof Faller
http://www.aes.org/events/146/papers/?ID=6559

Friday March 22
B-Format Decoding Based on Adaptive Beamforming
Alexis Favrot and Christof Faller
http://www.aes.org/events/146/papers/?ID=6566

An interesting tutorial is held by Lasse Nipkow, comparing native 3D music production to upmixing:

Wednesday March 20
Strategies in 3D Music Production (Upmixing vs Productions Aimed for 3D)
Lasse Nipkow
http://www.aes.org/events/146/tutorials/?ID=6582

Come and listen to great native 3D music productions, and compare them to Illusonic Immersive Upmix!

Hope to see you in Dublin!
 

There are only limited possibiliites in post-production for live for VR recordings (A or B-Format).

Illusonic Spatial Equalizer inputs A/B-Format and outputs B-Format.

Different objects and instruments can be equalized separately, including changing their gain.

While scheduled for an IAP release 7.1, coming in Spring 2019 time frame, I got very impatient to try the new Dynamic Range feature under real-world conditions.

While we have had computational complexity in mind during development, Dynamic Range turned out a bit more complex than originally expected. Take the maximum-case, where a 7.1 movie is applied to it:

8 channels and 4 subbands makes effectively 32 audio channels to be processed. On a memory sparse DSP, a challenge.

Alone the crossovers need 96 biquad filters!

Additionally 16 filters are used for loudness weighting and another 24 filters for filterband equalization - a total of 136 biquad filters !!!

Besides of the filters, the expanders/compressors process the 8 channels of each of the 4 subbands.

Managed to get it to run on the second day of DSP integration work. Running IAP at maximum processing case (room eq, crossovers, bass management, 7.1-in 15.1-out immersive), the DSP has 74% and 96% processing load without and with Dynamic Range, respectively! IAP without Dynamic Range now requires a bit more processing load, since I had to move some memory from Immersion to slow external SRAM.

That is, without detail optimization, we just tightly made it! Plan to optimize a bit later, to get again more DSP margin.

During focused music listening - at relatively high volume, in a relatively quiet environment - a listener can enjoy the dynamics, the way it was intended by the recording producers. When music is being played softer than for what it was mixed and mastered for, large dynamic range requires extra listening effort on the softer parts of the music, causing fatigue or loss of focus. A noisy environment makes the issue even worse.

It would in a way be desirable that one could adjust the dynamic range of music to one’s liking and listening situation. This is exactly what Illusonic’s new Dynamic Range (DR) technology does. DR can be set between 0 and 100%, whereas 0% puts music to constant loudness, 50% reduces dynamic range by half, and 100% keeps the full dynamic range (= DR off).

Technically, DR is implemented as a multi-band expander-compressor, with individual parameters for each band. While each band acts individually to prevent overall gain modulation, the bands are jointly controlled, avoiding spectral changes and coloration.

Having recorded, mixed, and mastered more than 1000 music productions, Patrik Schwitter has the ideal experience giving input for and tuning DR. Prior to the tuning sessions, he gave input on what he would need and the specific multi-band decomposition. 

Last week, we started tuning DR for its most difficult operating point, 0%, that is constant loudness music reproduction. This is the most difficult case in terms of artefacts and undesired changes to the music. Today Patrik Schwitter came for a second full day to tune DR. The parameters for the different bands were individualized to further optimize quality. Last but not least, the scale from 0 to 100% was optimized and its 50% point determined.

“I find it surprising, that there are no artefacts, very natural, like the music interpreted with less dynamics,” said Patrik Schwitter after his tuning sessions.

I am surprised, too! The goal was clear, but I was not sure how good the result would be. This algorithm is not an auto-gain-control type of volume adjustment, but kind of a dynamics-remastering. You do not hear volume follow, level is right there, right away.

A couple of anecdotes from the tuning session:

Patrik tested with Jazz music he recorded many years ago, where from his point of view now, he kept a bit too much dynamic range in the recording. A perfect test case, which worked well, like remastered with less dynamic range.

Another interesting case was “Nickelback” where pink noise type music suddenly transitions to solo singer and one hears the brickwall limiter of its original mastering follow with a delay. Interestingly, in this case DR reduced the pumping, it worked like inversely to the recording’s inherent limiter, making it sound more natural. (I don’t claim things sound always more natural with DR, this was an interesting particular observation).

https://www.facebook.com/illusonic

Current IAP owners can upgrade their IAP to HDMI 2.0b for CHF 800.00 (Swiss Francs) plus shipping.

Inputs 1 and 2 are configured for HDMI 2.0b / HDCP 2.2.

Inputs 3 and 4 are configured for HDMI 1.4 / HDCP 1.4, because many legacy devices out there do not know how to handle HDCP 2.2.

Supported 4k formats:

>4K @ 24/25/30Hz, 4:4:4, 8bpc = 297MHz
>4K @ 24/25/30Hz, 4:2:2, 8/10/12bpc = 297MHz (used for HDR)
>4K @ 50/60Hz, 4:2:0, 8bpc = 297MHz
>4K @ 24/25/30Hz, 4:4:4, 10bpc = 371MHz (used for HDR)
>4K @ 50/60Hz, 4:2:0, 10bpc = 371MHz (used for HDR)
>4K @ 24/25/30Hz, 4:4:4, 12bpc = 445MHz (used for HDR)
>4K @ 50/60Hz, 4:2:0, 12bpc = 445MHz (used for HDR)
>4K @ 50/60Hz, 4:2:2, 8/10/12bpc = 594MHz (used for HDR)
>4K @ 50/60Hz, 4:4:4, 8bpc = 594MHz

Main points:
– Reborn Feeling – improved menus, usage, new auto-zoom, new owner’s manual
– Another major step forward in Depth/Immersion
– Quality, Quality, Quality – many more improvements and extensions, see below

The update is available here.

Reborn Feeling

You instantly will notice usage refinements. Starting from the new minimalistic “Welcome” and “Bye” messages on IAP’s display.

Or, when you are far away from IAP, you are now able to read the display. Auto zoom adaptively magnifies the most important information on IAP’s display. For example, when you change volume, you see the current level large on the display.

The complexity of menus is now hidden for normal usage. You can now change sound presets without going to the sound presets menu, and always modify volume.

Ad hoc settings are now accessible by the touch of a button. Ad hoc settings allow you to adjust the sound temporarily. For example, change balance or subsonic filter.

The included all-new owner’s manual is fully up to date with IAP 7.0.

Sound: Immersive Meets Audiophile

In 2011, when we took on the challenge of designing IAP, we also took on the challenge to refine an upmix-like technology to an audiophile level. It is not that we had started from scratch. We were already several years on the market with several third party upmixers, including a market leading broadcast upmix processor (used by BBC, Sky, etc.).

But what a mix! Swiss Made audiophile hardware plus an unorthodox audio algorithm! No one has had the same problem statement as we did. And seven years later, we have achieved more than what we thought was possible. Illusonic Immersive by now sounds so amazing that we are not shy to show it before any audiophile audience. Usually people are puzzled. If we don’t tell them, they do not notice any effect, nor think it is not anymore stereo, just get great sound. Often people do not notice – until we switch to bypass – then a wonderful world collapses into a one-dimensional experience.

Quality, Quality, Quality

With this next major IAP update, we have again shown that we long-term support our audio processors. In the consumer domain, it is just normal that after a year or so, hardware is not supported anymore. In High End Audio, companies often lack enough software expertise to support customers well. Bugs are not fixed for years etc. For us it is normal to fix serious bugs within days. And about half of IAP’s features originally go back to customer requests (more coming…!).

Today the quality of a device is often largely determined by the quality of its software and firmware including dsp software. The audio quality of IAP hardware is at a level that other factors are the determining sources of limitation (amplifier noise, recording noise, loudspeaker non-linearities, room acoustics). The differentiating quality and potential lies in the firmware/software! Welcome to the world of IAP.

Detailed List of Additions and Improvements

Below is a detailed list of changes of this latest update, compared to the previous major update version (Summer 2018 Update).

Firmware IAP 2/4/8/16

– new Owner’s Manual for all IAP models

– major menu overhaul & auto-zoom to be visible at long distances
– new welcome and power off screens (“Welcome”, “Bye”)
– improved access to ad hoc settings (balance, dsp info, …)
– added support for ?|/& characters
– renamed orientation to “Mode” and moved to Immersive menu
– renamed sound settings “Immersive” to “Illusonic”
– multi-room: improved channel naming
– simplified menus (complex settings now only in IAP Configuration software)
– improved future backwards compatibility if characters are added/removed
– fixed a number of small bugs

– major revision of Depth & Immersion
– improved LR balance, now applied on stereo input (as opposed to output)
– fixed debug mode, has not worked for a while…
– added new club, hall, stadium modes (orientation)
– major bass management extensions (more flexible crossovers)
– when center strength = 0, set center diffuse sound to off (so center is 100% silent)
– added dsp image and copy protection for IAP 16 mk2

– modified power-on timing for new gen 2 main PCBs and DAC boards
– support of mk2 main board features (phono options, dig out)
– changed DSP output routing to match native DAC board (IAP 8, IAP 16 mk2) channel order, this also fixed IAP 16 mk2 dig out

IAP Configuration Software

-rename: IAP Controller => IAP Configuration !

-OSX: switched from i386 to universal (32/64 bit)
-OSX: now developer-sign application
-renamed IAP Controller to IAP Configuration
-added new bass management crossover options
-added support for ?|/& characters
-replaced EQ icons with popup menu
-added new club, hall, stadium modes (orientation)
-renamed sound settings “Immersive” to “Illusonic”
-bug fix: revert IAP now also reverts loudspeaker setup
-multi-room: improved channel naming
-added new phono options for IAP 16 mk2

IAP Calibration Software

-OSX: switched from i386 to universal (32/64 bit)
-OSX: now developer-sign application
-added new bass management crossover options
-active crossover optimisation workflow improvement
-new option to apply LP/HP filters (also when eq is off)
-added high pass option to time-domain plot (in addition to lp, bp)
-fixed issue with channel linking for mute/unmute
-improved positioning of eq curves, previously if max eq gain was more than 6dB it would go out of the figure, no it adapts automatically its vertical position
-improved absolute impulse response alignment
-multi-sub-combination time plot improvement
-now there are three channel linking configurations (before: 1)
-when no IAP is connected when launching IAP Calibration, it will as opposed to read the loudspeaker setup from IAP, ask the user to specify it
-bug-fix: when loudspeaker gains and low-cuts are used during measurement, gains impulse responses could be wrong
-bug-fix: eq on gain was not correctly written to export config .iap file
-bug-fix: some crossover related functions did not always work properly (functions which have if lp or hp, then…), this could also result in that a crossover would not be disabled during measurement
-bug-fix: spk size did not properly real-time sync with IAP
-various small improvements and bug-fixes

In a way, it acts like adding absorbers and bass traps to your room. A more in-depth discussion is below.

The Summer 2018 IAP Firmware/Software updates all IAP models to the latest state. Below are highlights and a detailed list of changes.

The update is available here.

Shown with Great Success at High End Munich

We showed a pre-release version if IAP 6.1 at High End Munich a few weeks ago.

Hiding audio equipment behind a sound transparent wall, people came to our room, more to listen, less to look.

We have never gotten as positive feedback on the sound on a show before. We have had surprisingly transparent sound, people noticed that by listening. No need to talk about it.

Clarity

What is Clarity?
Clarity can be fine tuned from off to maximum. When you enable clarity and increase it, you’ll hear this:

there seems to be less interaction of the sound with the room

bass becomes more defined

a bit like if you’d use absorbers and bass traps

sound is more intimate, instruments are more in your room (versus playback of instruments recorded in another room)

How Does Clarity Work?

Obviously, what Clarity does perceptually, is physically impossible! We can not modify a sound signal prior to playback such that the room acts as if it would have more absorbers and bass traps. In the following, different lines of thoughts explain Clarity:

1
Believe it or not, but good musicians will adapt to the acoustic. For example, if you have an acoustic bass player in a bass-resonating room, he plays differently, to make it sound nicer under the given acoustic conditions. This also works for other acoustic instruments, such a violins.

From this perspective, one way of viewing Clarity, is, that it slightly modifies the music to sound better under too reverberant conditions. Strength of Clarity can be controlled, i.e. the degree to which the music is modified is adapted to the user’s acoustic conditions.

2
Clarity works differently for bass and higher frequencies. Due to multiband limiting, music has often a continuously rumbling bass. And it becomes worse, if additionally the listening room has bass resonances. Clarity also restores more dynamic range in the bass.

3
Different sound engineers do their mixes differently. But there is not a single mix which is optimal for all acoustic conditions. For example, if you have a reverberant room and if you are far away from the loudspeakers, a dry mix will do better than a reverberant mix.

From this perspective, if your room is too reverberant, or if you are far away from the loudspeakers, Clarity will modify the mix such that it works better under these conditions. If the given mix is already dry, Clarity will do nothing.

4
Well known in virtual acoustics, mixes should be done from dry sources, because when you apply a reverb on a source which has already reverb, the result will be sub-optimal. Clarity counteracts two cases of “reverb-cascade” problem: reverb in the mix and your room’s reverb, reverb in the mix and Illusonic Depth/Immersion.

3-Stage Optimisation

Story

It’s Simple!
While it takes skills and experience to optimise a room, we have a simple solution:

1
It is easy to measure your system and room with IAP Calibration software.

2
Send us the data plus documentation.

3
We’ll optimise Calibration, Clarity, and Immersion for you.

We are open. If you love to play with things, you can. You have the same software as we do.

Calibration, Clarity, and Immersive
IAP Calibration software allows to measure a sound system multi-point and to optimise it linearly. The resulting room eq (and if applicable crossovers) reduce bass resonances and undesired coloration of sound.

In rooms without extensive acoustic treatment, after Calibration, things are better, but still not ideal. Clarity allows you to go a step further.

Depth/Immersion (short: “Immersion”) does the opposite. It adds again more room sound, but without adding coloration. Like this, sound can be made more spacious and enveloping.

Detailed List of Additions and Improvements

Below is a detailed list of changes of this latest update, compared to the previous major update version (Spring 2018 Update).

Firmware IAP 2/4/8/16

new function “Clarity”

improved dereverb before depth/immersion

improved depth (cleaner, yet wider sounding, better on reverberant voices)

remove immersive dry center option (for now just hidden, always off)

retuned depth/immersion scale to improve 50% default

IAP Controller Software

added Clarity to Immersive Settings

fixed some dialog boxes not showing correctly under Win 10

remove (hide for now) dry center function, always off now

IAP Calibration Software

added support for Clarity

fixed some dialog boxes not showing correctly under Win 10

In collaboration with ECAL Lausanne art school, Illusonic implemeneted an 12.1 immersive sound system within a Montreux Jazz Archive themed compact car called “Nina”. The result is shown at this year’s Montreux Jazz festival.

http://www.epfl-ecal-lab.ch/work/mjhl3/

This year, Illusonic will again exhibit at the worlds large Hi-Fi exhibition, High End Munich 2018. We are just about sound and will again feature a sound transparent wall STW to hide the audio equipment. Just listen, it’s just about sound! You can look behind the STW, to see which modern precision audio components enable the amazing sound. Optimised by an Illusonic Audio Processor IAP.

Timeless Quality

A lot of RD went into IAP since last year. IAP is the audio processor evolving constantly, without a need for hardware upgrade. Our first 2011 model gets still, and will for long, get new firmware software updates. Our goal ist to build timeless audio processors, timeless Preamp-Processor-DACs, with the most innovative and best signal processing inside.

For Whatever Scenario

The various models IAP 2, IAP 4, IAP 8, IAP 16) cover any imaginable application scenario, from audiophile 2-channel stereo, to active cross-overs, to subwoofers, to multi-channel and immersive audio, and multiroom systems. Illusonic’s service optimizes any of these scenarios in an unprecedented way.

Three main features

Spectacularly Immersive

Listening with different orientations

IAP Calibration 6.0

The Spring 2018 IAP Firmware/Software updates all IAP models to the latest state. Below are highlights and a detailed list of changes.

The update is available here.

Spectacularly Immersive

Depth/Immersion now more spectacular and more clean.

Amazing how sound becomes more spacious, even with only two loudspeakers. Not to mention the immersion which is generated with multi-loudspeaker setups.

We have put months of effort into revising IAPs’ Depth/Immersion algorithms. A goal has been to make their effect more balanced across different music. Ideally a single Depth/Immersion setting should work well for all types of music. We have come closer to that goal, by introducing new mechanisms which automatically adapt Depth/Immersion levels to the source – like a couple of little sound engineers hidden within IAP, actively mixing Depth/Immersion.

Additionally, we have improved the de-reverb algorithms on Depth/Immersion inputs, to “un-cloud” the signals before generating early and diffuse reverberation. This makes sound cleaner in general and prevents unpleasant “reverb cascade” effect.

Listening with Different Orientations

Orientation is a new feature, apply to any loudspeaker setup with surround channels.

By the touch of a button, you can change the orientation of the sound:

frontal: default listening, sound stage is in front

rear: sound stage is reproduced by surround loudspeakers

side: sound stage is on left or right side

party: sound is reproduced from everywhere

Why would one want to do this?

Well, why not once listening with an orientation towards the window? Or have a joint-audiophile and movies setup, where frontal orientation is used for movies and rear orientation for music?

Orientation works by the touch of a button! All is automatic, all is always optimal. Immersive keeps working. Calibration and crossovers remain optimal.

You can define an orientation in each sound settings preset.

IAP Calibration 6.0

A number of installers and sound engineers have been using IAP Calibration and have enjoyed its real-time operation (as you move controls, sound reacts instantly, like on a mixing console) and numerous AB comparison options.

We have enhanced and improved IAP Calibration based on pro user’s feedback:

faster real-time operation, AB now always instant, before/after also instant (this required also changes in IAP’s firmware)

new current eq (and linked eqs) enable/disable to quickly AB listen to one eq

new eq overal gain, for improved AB comparison eq versus eq bypass

new improved subwoofer/crossover features, aiding time alignment, bass cancellation calibration, etc.

Detailed List of Additions and Improvements

Below is a detailed list of changes of this latest update, compared to the previous major update version (Winter 2018 Update).

Firmware IAP 2/4/8/16

upmix 6.1: depth/immersion improvements

extended output gain trim range to +-12dB, added channel mute option

new features eq gain and orientation

improved timing smoothness, less display/communications blocking when changing params

IAP 2/4/8: increased max preset name to 14 characters (full display width, before 12 char)

fixed bug in update script, which would fail update of HDMI 2.0b chipsets

IAP 16: fixed bug, SUB (ch 16) can not be channel copy destination

fixed bug, where when Immersive was off, it was not entirely switched off

fixed bug, where new LP/HP types were disabled when eq was set to off (now all LP/HP always on, to keep crossovers always on)

IAP Controller Software

added warning when .iap file is from different version

added warning when .iap file is from different version

loudspeaker setup dialog: -disable sub as copy location for channel copy (not supported)

support new features: eq gain (outputs) and orientation (presets)

support extended IAP gain trim range and new channel mute

improved forward/backwards compatiblity between IAP firmwares

accelerated communication with IAP

IAP Calibration Software

improved audio handling

improved audio handling

new measurement gain for each loudspeaker, this is useful in special cases when gains highly vary

workflow improvements

new disable selected eq function (great for AB listening)

there there is a button “Apply BMGT XO” to apply bass management crossovers’ on all plots where applicable

now one can include only subwoofers in plots

spk include now respects channel linking, if on that is whole ch link group is added/removed

phantom sub is now only shown for included subs -so one can investigate performance of any subs combinations

waterfall plot: added time-range parameter

time plot added filter option, aiding crossover phase alignment

accelerated communication with IAP, especially noticable when using revert and before/after functions

add individual loudspeaker gains for measurement (expert feature)

support extended IAP gain trim range and new channel mute

many small improvements & bug fixes

The Winter 2018 IAP Firmware/Software updates all IAP models to the latest state. Below some highlights and a detailed list of changes.

The update is available here.

Center

While the Winter 2017 release brought major improvements to the Depth and Immersion, this release incorporates a major improvement to the Center center, released after more than 5 years of development.

While we thought that our previous center channel worked very well,  it has only been now, in comparison to the new algorithm, what additional potential there was!

The new algorithm works in 97 frequency bands – more than the number of keys of a piano! This allows separation of simultaneous tonal instruments, such as a soloist center violin, while other off center strings are playing.

Also, the new algorithm works with stereo phase and delay differences, preventing any timbral coloration when left-right delays occur in a recording. At higher frequencies, similar to the human hearing system, delay differences between the frequency-band temporal-envelopes are considered. Thus, even left-right uncorrelated signal is now routed to center when needed. The result is a center channel which sounds brilliant and full band.

Softwares

IAP Calibration has been improved in many ways. Here a few new features:

Automatic detection of bad levels during measurement, and notification to user

Auralization improvements, enabling yet better Illusonic Calibration Service (new auralizaton presets, improved signal processing)

IAP Controller has been updated to support the new upmix/center feature.

Detailed List of Additions and Improvements

Below is a detailed list of changes of this latest update, compared to the previous major update version (Spring 2017 Update).

Firmware IAP 2/4/8

added Illusonic upmix 6 (new center + improvements)

center on/off/on mutes sound to prevent switching artifact due to center’s new C=>LR crossover

fixed bug in firmware versions 5.x, where input delay was not always changed when switching inputs

improved dsp muting

update HDMI 1.4 firmware, version 0B-27-06

added support for future HDMI 2.0b boards

added more characters for strings (+, :, !, *)

added new dsp info menu (real-time info) and removed corresponding secret menus

Firmware IAP 16

added Illusonic upmix 6 (new center + improvements)

center on/off/on mutes sound to prevent switching artifact due to center’s new C=>LR crossover

fixed bug in firmware versions 5.x, where input delay was not always changed when switching inputs

improved dsp muting

update HDMI 1.4 firmware, version 0B-27-06

added support for future HDMI 2.0b boards

added more characters for strings (+, :, !, *)

added new dsp info menu (real-time info) and removed corresponding secret menus

IAP Controller Software

modifications for upmix v6 (hide matrix option)

added more characters for strings (+, :, !, *)

IAP Calibration Software

added measurement levels safeguard

now measurement is interrupted when mic level is not reasonable, user is notified

Current IAP owners can upgrade their IAP to HDMI 2.0 for CHF 800.00 (Swiss Francs) plus shipping.

Technical Details:
Supports 4K @ 24/30/50/60 Hz on all inputs with HDCP 1.x support. HDCP 2.2 on HDMI 4 input for high value (4K) HDMI 2.0 content

Firmware update of IAP retains all settings. Without any further work, IAP will function as before. Also, the latest IAP softwares can open files from previous software versions.

For given settings, the sound does not change. Only if for example the new equalisers are explicitly used, will sound change, over previous IAP firmwares.

The update is available here.

New Equalizer Types

Previously six parametric equaliser types were supported (Bell, low/high shelving, low/high pass, allpass). 17 new types have been added. Primarily the intention was to provide many more options to optimise cross-overs. IAP Calibration fully supports all new equaliser types.

IAP Calibration

A major update of IAP Calibration is included in this IAP update. The most powerful acoustic measurement/analysis/simulation/optimisation tool available, has been further advanced. Besides the dozens of improvements, distortion measurement has been added. Making it easy to detect issues in your HiFi system (defects, undesired vibrations, etc.).

Detailed List of Additions and Improvements

Below is a detailed list of changes of this latest update, compared to the previous major update version (Winter 2017 Update).

Firmware

fixed bug, where SPDIF input could be unreliable

added support for many new EQ types

fixed bug related to source input delay

if no center channel, or center strength=0, FL/FR are passed through bit-identically, as in bypass

IAP Controller Software

added strict condition to work only with current IAP firmware

added support for 17 new EQ types

IAP Calibration Software

added strict condition to work only with current IAP firmware

added support for 17 new EQ types

added function to save plots as high resolution .png files

new distortion analysis tool

distortion panel with many options

distortion analysis feature in time plots

increased max number of microphone positions from 24 to 32

improved plots: now thicker average lines are behind

improved precision of time plots (more points, etc.)

improved amplitude range handling for time plots

fixed a drawing issue of time plots on the left edge

improved y-axis ticks (adaptive number of ticks)

made automatic gain/delay estimation more precise

fixed bug with normalization of measurements

now peak is shown after measuring each mic position (before it was only shown after the complete measurement series)

fixed an incompatibility with files of old IAP Calibration version

fixed bug where subsonic filter was not simulated if bass management on but inactive (quite a rare scenario)

major update of verification measurement feature

fixed bug where gain-delay/eq/bmgt/tone-control on/off would not properly switch IAP (was not an issue during normal operation)