Hands down the best speakers I have ever owned, a list which includes extensive time with Monitor Audio Silver 9i, Monitor Audio Silver 10, B&W 684, Focal Chorus 806v, Dynaudio Audience 80, Mirage m-890i, etc, etc, etc. The level of detail in the ATC SCM 20 can only matched with electrostatic panels, which have other faults that the ATC doesn't have.
The bass could be a touch deeper considering these are bookshelves (50lbs each!) BUT it is deep, tight and accurate enough to deliver the goods even when listening to electronica or rap. Add a front firing sub accurately aligned & positioned and it's the best.
They aren't the prettiest to look at frankly, but they absolutely can get forensic on a music track, revealing details and conveying information other speakers don't. Bad classical recordings, of which there are many, will come through. Mine are paired with a Krell amp and Primare preamp and I'm guessing low quality equipment would also reveal itself with the speakers. I've heard some Tyler Acoustics and some Sonus Faber Cremona that could compete with these, but I think they were more "musical" and colored the music more than these do.

There is a big talent hiding in the small 20 Cubic foot. It is a chanllenge to pull that off. It saving me time wondering or asking myself for another upgrade.

My friend has ATC SCM-20. I have spent a lot of time in his house trying to find a weekness of the speaker. Trying all kinds of music. At last, I brought my Aplifier and CD player to his house, My gear seems to work well. I then purchase a used pair from AudioGON. After a week, the speaker arrived, I called in sick. So I can check the speak, hook it up, and start to listen. It worths calling a day off. I listen to one record after another. Then I realize, I have been turning the volume up a bit more and more. The ATC takes it and performs without holding back. I have reached so loud, I have never done to my old Bose. with 3 other floor standing speaker. I do a blind AB test with my friends. ATC beats everyone else. All my friends agree that without seeing, it sounds like full size speaker set. One of my friend ran back and brought his MK 336. We hook them up. Again, ATC takes it and pushes himself to another level. There is some minimal power needed for ATC. My original HK 8000 is just good enough to make the ATC going. I am now hunting for a big AMP.

lots

none so far

Great speaker with great slam,transparency,details yet quiet awesome deep tight bass(seal box)small speaker with big sound...etc etc yet to discover

ALL

can't find any but needs power like 150WPC

I was playing with a pair of Wilson5 for few months but find that it sound very hifi.Lacks of emotion,highs are dry not transparent bass boxy so is the lower mid.Music is floating not slam so when to a secondhand dealer to trade it in.So I tell the salesman my problem.He recommended a pair of ugly looking speaker(ATC SCM 20)told me I'll love it.My wife doesn't like the look of that speaker but the shop was kind enough to loan it to try.WOW WOW was my first test on Wilson test disc.My wife and I was amazed so are my friends who are paying much more for their speakers.I end up spend 4 hours a day on music rather than HT.The SLAM,DYNAMIC,EXCELLECT SPEED ,TEXTURE,TIMBRE RICHES,AIRY well the speakers just disappeared.This speaker specs.,I don't have but friends and I it will be around 32-20khz.

Similar Products Used:

Wilson 5,mini Utopia,B&W N805

plenty

cabinet not very nice

If you wanna buy a monitor speaker try ATC 10 or 20 U'll not regret.Is the best at its price.Is really one hell of a speaker.

Best quality materials, rugged, dynamic, transparent.

Lacks ultimate bass extension although the existing bass is surprisingly deep & tuneful. Limited product/dealer availability.

A superlative product that demands the finest ancillaries to sound its best. Incredibly accurate, detailed, dynamic, and with virtually no distortion, these speakers make discs of plastic sound like real music. Expensive, but worth the price of admission.

Similar Products Used:

Over 25 kinds of speakers over the last 30 years including B&W, Magnepan, 3A, Tannoy, etc.

Best quality materials, rugged, dynamic, transparent.

Lacks ultimate bass extension although the existing bass is surprisingly deep & tuneful. Limited product/dealer availability.

A superlative product that demands the finest ancillaries to sound its best. Incredibly accurate, detailed, dynamic, and with virtually no distortion, these speakers make discs of plastic sound like real music. Expensive, but worth the price of admission.

Similar Products Used:

Over 25 kinds of speakers over the last 30 years including B&W, Magnepan, 3A, Tannoy, etc.

Open, accurate and very detailed

Bass, need hefty power amp

ATC speakers are arguably not Hi-Fi speakers. They don't hide anything, so they show the weaknesses of other ancillary equipment, as well as bad recordings/source materials. High power amplifier is a must in order to get the best out of them. I used to use a pair of Audiolab 8000S+P to bi-amp them (75W+100W per ch) but that was not enough. The sound was detailed but fatigue-inducing after long listening sessions. The limitation in resolving power of the amp combination was also highlighted.
Changing to ARC tube pre-amp and the Theta dreadnaught (200W/ch) transformed the sound. I think ATCs do gel with tube (pre-)amp better.
True, in terms of transparency, the Martin Login is better. But the ATC gives more 'rythm-and-pace'. The Sonas Faber may be more relaxed and musical, but the ATC offers more resolution.
The B&W 804 offers similar resolution, better refinement, and a deeper bass. But the ATC sounds 'faster' and more accurate.
They are not difficult to position and will live in relatively small rooms (eg. 9 x 13 ft). They deliver a no-nonsense sound so you may not like what you hear if the source material is not good.

Similar Products Used:

Martin Logan Scenario, B&W 804N, Sonas Faber Signum

accuracy & dynamic range .these are without doubt the most accurate, lowest distortion,and loudest speakers you will find

expensive, low frequencies 30-60 hz requires a subwoofer to cover full range

atc speakers are mainly for musicians and audio professionals they are uncompromsingly accurate those who can afford/need the best use atc(sound studios/recording artists)

Similar Products Used:

scm0.1/15 subwoofer from atc

Extremely uncolored and accurate reproduction of music

No major weaknesses

The ATC’s were a delight to listen to from the first preview. The ATC’s will identify imperfections within the music source or system. It seems to dissect the music with great detail and an unfailing accuracy. The speakers quickly identify anomalies in the source recording that can be difficult to detect with other speakers. I listen to a wide range of music including classical, jazz and rock. I am pleasantly surprised to hear subtleties that I never noticed previously. Superior recording give you the feel of being at the recording studio and believing the artist is in your listening room when you close your eyes.

My only minor criticism is the imaging. The speakers present a good sound stage but are surpassed in this one area by some speakers in the much higher price ranges.

The workmanship is first-rate, ATC offers a range of quality veneers. The weight is surprising the first time one lifts these modest size speakers and realizes the quality of the workmanship. I continue to be impressed with the ATCs and consider them a wonderful value for the price, especially after hearing speakers more than triple the price that deliver less quality.

Similar Products Used:

Various KEFs, B&Ws, Revel,etc.