APL Virtuoso v2

Screen 1: Virtuoso’s default View page.

Based on cutting‑edge psychoacoustic research, Virtuoso v2 aims to deliver for headphone users the most convincing emulation of ‘speakers in a room’ to date.

APL Virtuoso is a plug‑in and standalone binaural renderer built on technology developed by Dr Hyunkook Lee, Professor of Audio and Psychoacoustic Engineering and Director of Applied Psychoacoustics Lab (APL) and the Centre for Audio and Psychoacoustic Engineering at the University of Huddersfield. The core psychoacoustic 3D modelling technology of Virtuoso is known as ASPEN (APL Spatial Audio Engine) and, along with its use in Virtuoso v2, APL say that it will soon be available for licensing.

Virtuoso lives in the same kind of territory as Stephen Slate Audio VSX, Sonarworks SoundID Reference Virtual Monitoring, Acustica Audio Sienna, Dsoniq Realphones, and Waves Abbey Road Studio 3, in that it aims to deliver over headphones a representation of the sound and spatial quality of monitors in a room. However, rather than modelling only stereo monitoring, Virtuoso is able to model a comprehensive variety of multi‑channel immersive formats. Everything from, say, 5.1.2 Atmos to Auro 3D 13.1, and numerous varieties in between. At the time of writing, I believe only Acustica Audio Sienna, among the similar products I mentioned above, can work beyond stereo.

Overview

The standalone version of Virtuoso is available for both Windows and macOS, and its plug‑in version covers AU, AAX and VST3 formats. The specifics of the integration of the plug‑in within a DAW session will depend very much on the channel width of the session and personal routing and workflow preferences, so beyond simply installing the plug‑in and checking its functionality in Pro Tools, I concentrated for this review on using the standalone version.

Once installed and running (which requires iLok authorisation), Virtuoso can model 53 different monitor configurations, from mono to 26 channels, including immersive audio formats such as Dolby Atmos, ITU‑R, Auro‑3D, MPEG‑H and Ambisonics arrays. Any of those monitor configurations can be heard in seven different virtual rooms with customisable acoustic parameters such as ambience, reverb time and listening distance. Virtuoso also offers headphone head tracking support, headphone response compensation with 100 stored headphone models, monitor frequency response modelling with 11 stored monitor models, routing and downmix options, and 10‑band parametric headphone EQ. Finally, the standalone version of Virtuoso offers WAV and ADM (Dolby Atmos delivery format) file playback.

The View Page

Screen 1 illustrates the Virtuoso View page; effectively its home page. The main graphic displays a representation of the currently selected monitor format (Atmos 7.1.4 in this case), which it (somewhat confusingly, I found) refers to as the Input Config. Each monitor in the display can be clicked to solo and Option‑clicked to mute. Before I move on to describing the functions located below the main graphic, there’s actually a really important configuration parameter hidden behind the Options menu at the top right of the page — one that took me a while to find (before I’d read the manual of course). The Options menu includes an Audio Settings sub‑menu where Virtuoso inputs and outputs can be specified. You won’t get very far with Virtuoso ’til at least the output setting has been attended to. And if you’re wondering what the input is for, it provides an alternative routing option for playback. For example, I was able to route Apple Spatial (Atmos) material from the Apple Music desktop app into Virtuoso.

Moving down the View page, Room presets are selected from a drop‑down menu and include a variety of studio control room models along with a dubbing stage, a domestic living room and a domestic home cinema room. The room models, say APL, were “scientifically designed with ASPEN’s 3D geometric acoustic simulation and carefully tuned by Tonmeister ears. The APL Listening Room preset models the actual APL critical listening room that complies with the ITU‑R BS.1116‑3 recommendations. All of the preset rooms have different room dimensions and acoustic characteristics.”

Alongside the Input Config and Room preset menus are Ambience, RT60 (reverb time), Listening Distance and Gain adjustment knobs. The first three enable some modification of the Room preset and the last one is effectively the output gain control. Option‑clicking the four controls returns them to their default values but they don’t retain any adjusted values when a different room is selected. I found this slightly inconvenient because it means if I made adjustments and then switched to a different room, the adjustments were gone when I returned to the first room. I would have liked Virtuoso to have a facility to store user room presets (although of course that can effectively be done in the plug‑in version by saving a global plug‑in preset).

Below the room adjustment knobs are drop‑down menus to select headphone (HPC) and monitor (SPK) EQ presets. The headphone menu lists 100 popular studio headphones, including, as is apparent from the screenshot, one of my old favourites, the Sennheiser HD650. The range of monitor options is much less comprehensive at just 11 models, and in the drop‑down menu they are only identified by letters, so you have to read the manual to find out what they are. Worry not however, ’cause I’ve done that for you: Monitor A: ATC SCM11; Monitor B: ATC SCM7; Monitor C: Barefoot MM45; Monitor D: B&W 705 S2; Monitor E: Dutch & Dutch 8C; Monitor F: Genelec 8331A; Monitor G: Harbeth M30.2 XD; Monitor H: Neumann KH120A; Monitor I: PMC6; Monitor J: Q Acoustics 3030i; Monitor K: Yamaha HS5.

Finally on the View screen is a file player that enables the selection of an ADM or WAV format immersive file package for playback. Play, stop and scrub functions provide playback control. The playback function is not implemented in the plug‑in version of Virtuoso .

The Setting Page

Screen 2: The Settings page allows you to tweak parameters relating to the HRTF and room modelling.Screen 2 illustrates the Virtuoso Settings page. Controls on the right of the Settings page enable further modification of the room models with room dimensions, damping (absorption), and low‑ and high‑frequency reverb decay. A Room Loudness Normalisation option is also provided that equalises the apparent volume level that would otherwise change when room parameters vary.

On the left of the Settings page, starting at the top, are facilities to select between five generic HRTF presets or load a personal SOFA format HRTF. A channel mapping option comes next. Channel mapping provides a solution to the issue of different DAWs and immersive workflows potentially assigning different channel orders to immersive channel widths. Channel mapping offers 1:1 and Auto options. In 1:1 mode, channels get mapped to each Virtuoso input sequentially. This, say APL, is recommended for those working with Ambisonic material, or who find that their particular DAW operates in this way. In Auto mode, the channel names are used to map each channel to a corresponding virtual loudspeaker. This is the recommended mode for spatial audio formats such as Dolby Atmos.

Next comes the Downmix menu. Downmix enables immersive multi‑channel material to be heard downmixed as if the room were home to a monitoring or playback system comprising fewer speakers. Below the Downmix menu, a low‑pass filter can be engaged to enable manual routing to a Virtuoso virtual subwoofer. In the majority of cases I think such LFE routing or bass management is likely to be handled within the DAW session or embedded in the ADM playback, so the filter would remain off.

The final feature of this page is management of head tracking. My first exposure to head tracking was with the Audeze Maxwell I reviewed in the January 2025 issue, so I’d refer you to that for my thoughts on head tracking generally but, coincidentally, one of the headphone models with which Virtuoso head tracking is compatible is the Maxwell. I still had the Maxwell review sample to hand and firing them up with Virtuoso head tracking engaged worked extremely well.

Matrix & More

Screen 3: The Matrix page.The Matrix page, shown in Screen 3, shows the current channel assignments and provides Mute and Solo options for each monitor. These are the same Mute and Solo functions available by clicking on a speaker in the View page. The Matrix page also enables trim/gain to be applied to each channel. The assignments and channel gains shown on the Matrix page will vary depending on the downmix settings selected in the Settings page. Finally, the HPC EQ page, shown in Screen 4, presents a 10‑band parametric equaliser that, if a headphone EQ profile is assigned, shows the profile curve and enables its adjustment. If no headphone profile is assigned, the EQ will be flat and adjustable to taste.

Virtuoso’s Virtues

Screen 4: The HPC EQ page, which allows the headphone correction to be modified.I’ve been pretty comprehensively through the functions and aims of Virtuoso but does it work? Yes it does — and then some! I was genuinely blown away by Virtuoso’s ability to render over headphones a convincing multi‑monitor system and room acoustic. I began by listening to a particularly familiar ADM and found myself instantly at home with the sound. In the Virtuoso Settings page, I ‘built’ a virtual room, modelled on my own in terms of dimensions and reverb time, and picked not dissimilar virtual monitors (Neumann KH120) to play the role of my Dynaudio BM5 Mk3 Atmos system. Then I routed the Virtuoso output to one of the headphone sockets on my Audient ORIA interface so that I could quickly compare my real‑world Atmos monitoring with the Virtuoso virtual version over headphones.

It was a genuinely uncanny experience; all the panned Atmos elements ‘appeared’ in the appropriate places with a satisfying sense of precision and focus, and the room acoustic sounded not just real, but familiar. Soloing speakers from the Virtuoso View page was shockingly effective in demonstrating its power to localise sounds around, behind and above. More than once I removed my headphones to check that the actual monitors were muted.

Soloing speakers from the Virtuoso View page was shockingly effective in demonstrating its power to localise sounds around, behind and above.

Virtuoso’s virtual room and monitoring isn’t perfect, though, with the most noticeable divergence from reality for me (apart from the physical experience of wearing headphones) being level differences in terms of the intensity of some rear‑panned mix elements. However, tweaks to the channel gain settings in the Virtuoso Matrix page were pretty effective in bringing the presentation in the virtual room closer to the real room, and I’m sure more refinement in that respect would only improve things. Picking the most effective HRTF is also a significant factor in this respect.

Once I’d started getting such great results from Virtuoso and familiar ADMs, I couldn’t help but start trawling around Apple Music for favourite Apple Spatial tracks to see how Virtuoso would handle them. At that point however, any thoughts of formally reviewing Virtuoso pretty much came to an end — I moved on simply to enjoying what it can do. And what it can do is deeply impressive.

But does it signal the end of conventional monitoring? I don’t think so, because there’s still nothing quite like the sense of air moving in a room. But if you want to mix in Atmos (or any other of a multitude of immersive formats) and you can’t make space for, or afford, a multi‑channel monitoring system, Virtuoso is a hugely effective and capable alternative.