ATC SCM20ASL Speakers Review

In the HiFi world, active speakers often get overlooked, and it's only when you get to hear them in action that you start to realise the real benefits of going down this route. Active speakers are the most common type of speaker in PRO audio and studio settings, as they already include the best amplifiers built into the speaker. Therefore, you only need your preamp/DAC to play the music. ATC is one of the masters in this field, thanks to its 50-year-plus history, with most of its speakers and studio monitors being active. They still offer passive versions, but most studios and audio professionals choose the active version, and for good reason: they are among the best available. This does not mean that active speakers are not the preferred choice for HiFi enthusiasts, as many audiophiles prefer actives over passive speakers and for good reason: their performance is stunning, and they offer the benefits of fewer boxes and amplifiers typically required in your room for passive speakers.

Every time I listen to ATC active speakers, I fall in love with how they sound, and the last Bristol HiFi show was no exception, as they had the SCM20ASL Limited Edition speakers playing with their accompanying subwoofer in a gorgeous gloss blue finish. This was to celebrate their 50th Anniversary in 2024, and they sounded sublime. They were my favourite from the show this year. So, when ATC asked if I would like to review a pair of the newly released SCM20ASL speakers, it was an easy yes.

I have reviewed two of ATC's Entry speaker series, the SCM19A and the brilliant SCM40A, but this will be my first review of a speaker from their Classic series. The SCM20ASL is the smallest of this range, with the impressive SCM50ASL speakers sitting just above it. There is nothing entry-level about the SCM20ASL speakers; they exhibit all of the traits of their larger speakers in a smaller package and are ideal for modest-sized rooms. Using their vast experience, they have created a flagship active 2-way standmount speaker that combines the best drive units and amplification in a more manageable size, with all the performance, and is hand-built here in Gloucestershire, UK.

Build Quality and Features

I have always been impressed by ATC's build quality; their speakers are built like battle tanks, with such a solid build and exceptional craftsmanship. They are built to be heavy and inert, which helps prevent unwanted resonances from affecting the sound quality. The cabinets are constructed of Oak wood veneers, but can be ordered in various finishes. The starting price is £6,495, and depending on your choice, premium finishes can push the price to just shy of £9,000. Inside the cabinets, they are heavily braced and feature bitumastic damping panels at critical points. The black front baffle protrudes from the main cabinet, which houses the two central drive units, a tweeter and a mid-bass driver. ATC builds all its own drive units in its factory in Gloucestershire. The tweeter is designated as their 'S-Spec' 25mm soft dome with dual suspension drive unit, and the mid-bass is a 150mm/6" Super Linear drive unit —one of the most serious-looking drivers — and features a larger-than-usual dust cap, which gives it a distinct look. Everything about them screams over-engineered, and never a doubt that they can handle serious abuse. This is a sealed box design. On the rear of the unit is the amplifier pack, which houses two separate power amplifiers: one 50-watt amplifier for the tweeter and a 200-watt amplifier for the mid-bass driver. The amplifier plate features one XLR connection for connecting the speakers to your preamplifier, a power supply input, an on/off power button, and a bass shelf cut/boost dial so you can tailor the bass level to your room and position. Thankfully, because they are a sealed-box design, they are much easier to position and can be placed close to walls. Even though they are the smallest in the ATC range, they are still reasonably large speakers, weighing nearly 25 kg each, so a sturdy set of stands is recommended to support them. Also, a relatively strong pair of hands is needed to pick them up; thankfully, the amplifier plate has handles, which makes them a little bit easier to handle.

Specification List:

• Mid/Bass driver: 1 x 150mm/6", SB75-150SL 8Ω
• High Frequency Driver: 1 x 25mm/1", SH25-76S 6Ω
• Low Frequency Cut-off: 55Hz (-6dB, anechoic)
• High Frequency Cut-off: 25kHz (-6dB) Matched Response: +/-0.5dB Crossover Point: 2.2kHz MaxSPL: 108dB continuous, 114dB peak (per pair, IEC Weighted Pink Noise, 1m, anechoic).
• System Sensitivity: 85dBC SPL (@1m, pink noise, -18dBu, 1V input sens. 0dB bass boost).

• Balanced Input: 1 x Rear Panel Mounted Female XLR, pin 2 hot Input Impedance: 20kΩ (differential)
• Input CMRR: >60dB at (10kHz)
• Input Sensitivity: 2.2dBu/1Vrms for full power Input Sensitivity Control: -6dB switchable, -6dB variable. Total adjustment 2.2dBu/1Vrms to 14.2dBu/4Vrms
• Bass Shelf: -2dB to +3dB, switchable in 1dB steps Crossover Filters: 2nd Order Linkwitz Riley
• Amplifier type: Grounded Source MOSFET, class A/B, convection cooled
• Output Power: Bass 200W (8Ω), H.F. 50W (8Ω) THD+N: <0.0017% /-95dB (1kHz, 1dB below rated power, 90kHz BW) Frequency Response: <2Hz to>200kHz (-3dB)
• Limiter: ATC Active FET Momentary Gain Reduction
• Electronic amp protection: Amplifier d.c. offset and over-temperature (both indicated by rear panel LED) Mains Input: 220-230V or 115V, factory set. Please observe panel markings and labels!
• Power Consumption: Idle 26W/41VA. ¹/₈th Power 116W/116VA. Full Power 312W/398VA
• Heat Output: Idle 89BTU/hr, ¹/₈th Power 311BTU/hr, Full Power 382BTU/hr

• Net Weight: 24.3kgs/53.6lbs
• Dimensions: HxWxD 450x250x411mm 

For this review, I am using the Cyrus Audio 40 Amp as the Preamplifier and connecting it with a pair of RCA cables, which are then attached to the XLR adapters to plug into the SCM20ASL speakers. For sources, I am using my Denon DP400 turntable, and for CD playback, I am using the brilliant Cyrus Audio CD40 player. For streaming, I have my Bluesound Nano Node streamer connected to the Cyrus 40 Amp. I have music stored on my local NAS drives, and I am also streaming music from Qobuz. Setting up, I am using my Atacama stands for the ATC speakers to sit on, and toeing the speakers into my listening position to sharpen up the imaging. I feel that I have them set up perfectly, as the imaging is razor sharp.

Sound Quality and Performance

My first album is on CD, and at the UK HiFi Show Live 2025 that I attended last month, I listened to a great track by Joe Bonamassa that I loved. I then purchased the CD after streaming it on Qobuz, as it sounded so good on my own system. It is his brilliant 2009 album Live at the Royal Albert Hall, so I just had to play it through the ATC SCM20ASL speakers to see what they could do for this stunning album.

Track 1 Django starts off with the crowd whistling and cheering as he comes on stage. The whole ambience of the Royal Albert Hall is perfectly rendered, with incredible imaging from the ATC speakers. The resolution and clarity these speakers produce are simply sublime. Joe Bonamassa's guitar comes into centre stage as the crowd erupts once again. When the drums come in behind him and to the right, they sound powerful, with plenty of snap, impact, and kick drum punch. The bass produced by the SCM20ASL speakers is extremely clean and precise. The imaging these speakers throw out in front of you is most impressive; it has incredible depth and width to the soundstage, and, with your eyes closed, you are transported to the Royal Albert Hall with all the space and ambience you get when sitting there in the crowd.

Track 5 So Many Roads is a beautful sounding track, his impressive band and specifically the drumming sounds so good with some spectacular moments which the ATC handles beautifully with real snap, punch, and power, transient shifts are lightning fast with no overhang, the bass driver starts and stops on a dime and the sealed cabinet of the ATC certainly helps the mid-bass drivers bass which is so fast, the brass horns section sounds so sweet with such a rich tuneful and powerful sound with excellent tonality, the ATC speakers have a real immediacy to the sound with so much energy and drive that you cannot help but love the stunning clarity and resolution of the music being presented in front of you.

Track 9 High Water Everywhere is my favourite from this album, and listening to it through the ATC speakers is an experience. With the volume turned right up, the drums fill the soundstage from left to right before Joe Bonamassa's guitar comes in with a tactile, real, tangible sound that you can feel as every chord is plucked, vocals are placed centre stage, and instrument separation is excellent. Still, it is the drumming that sounds so impressive, and how fast and powerful the bass feels from these ATC stand mounts, and considering it is a 6" bass unit, it most certainly packs a punch, it may not be the deepest of bass from a standmount, but it is the quality of the bass that you hear that impresses so much. The one thing I love about the SCM20ASL speakers is that they do not hold back; you hear everything in a recording, and they do not brush over any of it. These have to be among the most revealing stand mounts I have listened to, and I absolutely love the way they unveil the music on this album. Considering they are only a two-way standmount speaker, they manage to present the music with such convincing scale and grandeur that certainly defy their size, allowing the stunning acoustics of the Royal Albert Hall to be translated into your living room.

My next album is from the beautiful Sade and her magical sound. This album was initially released in 1984, but this is the 2020 vinyl reissue of Diamond Life. Sade's vocals are velvety smooth, and this is one of my favourite albums from this legendary artist. Her mix of soul and Jazz is something I loved the sound of back in the 80s, and it has not faded over time. Her beautiful vocals are timeless, as is her music, and this album is so well-recorded that I never tire of listening to it.

Track 1, Smooth Operator, is a classic from Sade, and the ATC speakers do not disappoint, revealing every detail with stunning clarity. The Saxophone has excellent tonality and projects well into the room, allowing for a holographic image of the music being played. Sade's vocals also sound wonderfully harmonised with the instruments, revealing the multiple layers of textures in her vocals. Percussive instruments, like the Conga, are defined by a subtle yet profound effect that is so rhythmically addictive. I am hearing so much more detail in the music than I have, say, with my ProAc speakers.

Track 2, Your Love is King, is most certainly my favourite from this album, and I love every track, but this one lets me reminisce about days gone by and the music I used to listen to when I was much younger. The Cyrus Audio 40 Amp phonostage is excellent; the amount of detail it allows you to hear through the ATC speakers is sublime, revealing the many beautiful layers of this complex track, which the speakers translate perfectly with incredible clarity. Once again, the Saxophone takes centre stage with stunning results on this track; the imaging is amongst the best I have heard from any speaker, especially a stand mount. Sade's vocals are silky smooth, and every instrument can be picked out within the soundstage, with plenty of air around them, creating a more coherent, believable soundstage.

Track 2 on side 2 of this album, Sally, was my least favourite, but listening to it through the ATC SCM20ASL speakers has changed that. I have been listening to it a lot since the ATC speakers arrived. The sound is sublime; the bass guitar has a beautiful, deep, rich tone. The drums and cymbals shimmer with such delicacy that the sound seems to float out in front of me. The soundstage is both broad and deep, and the speakers simply disappear, leaving Sade singing in front of me; the confines of my room and walls seem to have moved way beyond the speakers, giving a greater sense of depth and realism.

I have thoroughly enjoyed my time with these incredible standmount speakers from ATC; they really do extract every bit of musical detail and emotion from whatever you play. I have listened to so much music over the past couple of weeks and tried to cram in as much as I possibly could. I knew they would be good after I heard the Limited Edition SCM20ASL speakers at Bristol, and this has proved beyond any reasonable doubt that they are seriously capable standmounts. I would love to own a pair with the matching subwoofer. All you need is a capable DAC/Preamp, and you have a very high-end 2-channel system.

Make sure you check out my social media channels, as I have posted lots of videos of the music I have been listening to. Pink Floyd, David Gilmour, MEZERG, Joe Bonamassa, Sade, Orphan King and Go Go Penguin, to name a few.

Conclusions and Final Thoughts

The new ATC SCM20ASL is one of the most satisfying standmount speakers I have listened to, with razor-sharp imaging and an addictive, rhythmically satisfying listen. It provides a simple solution to all your music needs in a relatively compact standmount. No need to look for the perfect amplifier, as ATC has already taken care of that.

The Speaker Shack awards the new ATC SCM20ASL Speakers with an Editor's Choice award and stamp of approval.

Price at time of review: £6,495

Web - https://atc.audio/