ATC SCM 40 question


I recently bought a pair of ATC SCM40 speakers. I have them placed in a room approx 12ft sq. They are on the back wall, seating on opposite side. I can't move the speakers into the room or move the chairs into the room as I barely got away with buying these and can't encrouch any further, the missus was not happy at the size of them!

Anyway, they sound pretty incredible a lot of the time, but I've noticed on some recordings, not necessarily bad ones, just they can come across a little shrill and sharp, like the highs are overheated somehow.

I'm driving them with a PS Audio S300 Poweramp, that is being controlled by an RME ADI 2 DAC. 

I've tried messing with the dsp settings on the RME but I just can't seem to ease the issue.

My question is, does this seem like an equipment issue? Or maybe a cable issue?

I don't want to end up spending serious cash upgrading the amp or dac if that is not the problem. But I know the SCM40's need a lot of juice and the S300 only has 140w per channel, and the recommended is 150w. Or is that just a top end volume concern? I'm already looking at the Hegel H20, I can't get the ATC poweramp as I don't have the space for it.

Also I was looking at the Anthem STR Preamp. Something that might calibrate the sound better for the room. Maybe a cable upgrade?

Anyway, these are just my rambling thoughts on an ongoing issue, any advice at all would be much appreciated. I really want to solve this as when these speakers sing, they really sing!



we are a stocking atc scm 40 dealer


give us a call we can advise you

Dave and Troy

Audio intellect nj

Atc dealer 



That's a small room. Do you have any treatment behind the speakers or on the side wall at the first reflection points?

What kind of speaker wire are you using? Do you have them firing straight ahead? Try changing Toe-in, etc.. And yes, room treatment.

Are these new or the original version?  I don’t think driving your amp with the RME DAC is doing you any favors here so you might entertain adding a good preamp, and it’d be good to know what cables/interconnects you’re using.  Do you have a carpet on the floor?  Also, you could try to tame first reflections on side walls and maybe try putting some felt around the tweeters.  Just some thoughts FWIW. 


I know the feeling. Bought the SCM19v2, as that was all that was allowed.

You're right, they do like a bit of power to really let loose.

Were the SCM40s new? How long have you broken them in for?

Thanks for the replies everyone!

@jerrybj Yeah I was in the doghouse for a while. I went with the forgiveness over permission tactic, just about worked!

To answer the questions:

Brand new SCM40's. I've had them for about four weeks now. I listen everyday but have not done any specific 'burn in' process.

Chord Shawline X Speaker Cable

Chord Shawline Analogue XLR Cable 

Supra USB Cable

I'm sorry to hear the RME might be inadequate, I had thought it a perfect solution and would leave the PS Audio S300 to do all the work. So the preamp is still important even with a power amp in the chain? That leaves me in a quandry as I've got space constraints. The preamp can not be taller than 12 cm, and must also incorporate a high end DAC. Any recommends would be appreciated. I thought about the Anthem STR but I'm a bit put off by the dac chip apparently not being the best. 

As I say, this system is almost perfection, with the right recording that doesn't tickle the high end too much, the speakers sound unbelievable. Stick on a bit of Gordon Lightfoot, beautiful.


I'm steering towards the Sablon 2020 usb cable but fear it mightt be overkill.




I love my ATCs. End game speakers for me.

I ran mine in for 150 hours when I got them. Had them on loop when I went to work, dodging people at home.

I used to have QED Silver Anniversary speakers cables. Very bright. Have you considered the silver plated Shawline could be adding that sharpness?

I've built my system based on limited space. A cupboard 600x550x420mm with four shelves, including Blu-Ray player. System has to be hidden from sight, with no 'ugly' cables.

I use the Mad Scientist Black Magic USB cable. Very good.

Post removed 


Good point about the shawline series. Maybe that is an issue.

I'm looking at possible warmer options along the chain. Maybe the Phasure series, both XLR interconnects and lush 3 usb will do the trick. I'm intrigued by the flexibility to change the characteristics.

I do love the ATC's. I've owned a pair of SCM11's in my work studio for the past year. Wonderful nearfield speakers.

I’ve owned ATC 40 passives. I never experienced shrill/sharp so I know it’s not your speakers, an excellent choice I might add.

The 40 passives won the 2019 AZ Speaker Fest by a wide margin against seven other quality contenders, several of which were far more expensive. That system was all ATC (CDA2 mkII > P1 > 40) with Cardas wire.

Speaker/listening position and acoustics could be part of the problem, If you haven’t done so already, purchase Jim Smith’s Get Better Sound book. He has a great system for dialing in speaker/listening position as well as dozens of other tips that may help you.

Get Better Sound

You have a world class speaker. Please don’t give up on it.

I often wondered what a pair of scm 40’s would sound like in my 10 by 13’ room.I do have a pair of 19v2 on sound anchor stands that sound great in that size of a room.It just gets better with your setting up efforts.Small increments make a big difference in sound stage

I can only tell you from what i learned in my small room... toeing them in will avoid most first reflection...atc are really quite well behaved speakers in smaller environment.Contacting these guys cant hurt.Lone mountain as well.Learning about setup makes all the difference.I almost gave up as other poster wasnt the speaker’s fault it didnt sound right.


It's new speakers they need burn-in be patient

And don't do any changes now give them time .

Aside from burn being constrained about any other setup is hard to really suggest something thats going to make the difference having a speaker like that and not giving it at least some best case setup scenario...Youll never know what there capable of...and for that reason im out.😉...Youll have to just try stuff.


I agree with the above sentiment, I almost feel obliged to upgrade the rest of the chain now to give the speakers a fair shout. They feel like the one piece of a equipment I own that is, to quote Tom from Succession: "The bottom of the top"

With that in mind I’m thinking of maybe upgrading the Dac/Preamp from the RME to the HoloAudio – Spring 3 DAC Level 2.


Think about trying an inexpensive used Tube preamp or warmish ss preamp before you change the dac. Way more bang for the buck IMO. Can always sell it for what you paid if it doesn’t work out. 

Get those herbies sliders and you can setup ..shove them out of the way when done.

a few questions 


how are you driving the dac?

the source  does matter 

why not  trade in the ps audio for an really good   integrated amplifier ?


we run our scm 40s with great success with the unison research unico 150 a powerful hybrid amp the tubes  warm up the speakers while the  solid state power stage provided deep propulsive bass thuis amp is similar in rated power but has no issues driving the 40s 


the atc tweeter is very your dac could be the problem the s300 amp is not a class ab amp so between your dac and amp this is probably why the speakers are sounding a bit hot 


Dave and Troy

Audio intellect NJ

Atc Dealers 


I have them in a room facing a wall of windows, which creates a lot of brightness. My inexpensive experiment was getting a Loki and turning the two left knobs to about 2 o’clock. Problem solved.

“Anyway, they sound pretty incredible a lot of the time, but I've noticed on some recordings, not necessarily bad ones, just they can come across a little shrill and sharp, like the highs are overheated somehow.”

I may be oversimplifying things but. 
Seems to me common sense says we often focus on equipment and overlook source material.

If your speakers sound “incredible a lot of the time” …actually that would be the speakers, your system AND your room…then wouldn’t it make sense to assume the fault lies with those sources and not your system.

A revealing and neutral system would expose the sound quality of the tape, record, cd etc. So, is there a playback system that makes everything sound great all the time? Can a system be tweaked to address problem areas, and I assume we are dealing with frequency here, record or cd etc. Aside from “custom” EQ ing your system to eliminate problem’s with source material on an as needed basis, is there anything you can do?

ATC (I don’t have much experience with them, though I am considering the brand for purchase) are noted for being very revealing…they are often used as mix monitors by engineers for eg. With this level of detail the source material will be revealed. Bright recordings will sound bright etc.

I, in fact, would be a bit wary of any speaker or system where everything sounded great (or not so great). We do tend to prize transparency over coloration but is there a case of too much of a good thing?

I have no answer but this OP made me think.

Post removed 

THis is exactly the dilema we face in pro, when the "warts" make some people think it "sounds worse". To avoid this in record making, there's a secret method some top mixers use: turn on subs or even different [EQ’d] speakers for the clients to hear their mix, so their mix sounds better to them. If they heard it on the mix speakers (say NS10s, auratones), they would universally hate it and would not approve it.

This is a very complex area and extremely diffiuclt to explain outside of the studio.  Learning how to critically listen is perhaps the single most important "skill" a mixer/mastering engineer has to learn.  The truth is if you mix to sound good on an ultra revealing pair of speakers, it will sound good on everything else and likely be error free.

If you mix with a speaker that has bass boosted, it will turn out bass light on other speakers. If you mix it on a speaker that’s too dull, too rolled off, it will turn out too bright on other speakers.  If you hear a record that has no bass, theres a very good chance the mix/mastering speakers or the room was very bass boosted.  They were convinced there was bass where their wasnt.  If the crossover is an issue on your passives, there's a dip right there, you will want to eq to remove that dip in instruments around that crossover area, becasue the dip makes them sound weird.  Now the entire mix will sound like a peaky midrange, especially on a good pair of speakers that don't have that same dip.  

I have ATC SCM7 (gen 2) with the ATC house tweeter and the earlier ATC SCM35’s with the ScanSpeak tweeter. My SCM35’s are far less forgiving of hard and bright source material. My read is that you are getting a better rendition of what the material actually sounds like than you did before.

This has been true for me whenever I did a significant upgrade. 

I run tube preamps and solid state AB amps with both speakers. I have heard the latest SCM40’s several times and they are not hard sounding with good source material and good electronics.

As others have indicated, I would look to some basic room treatment before changing electronics.

I have the bigger 100ASLT in a room with treatment applied and have absolutely no issues listening to a very wide range of recordings. My dac/preamp is the very neutral Benchmark DAC3/HPA4, so no dumbing down or softening going on in the electronic chain. My listening sessions are often for many hours.

My first ATC's were the smaller passive SCM19's (which I still own). They replaced Harbeth M30.1's and I much preferred the ATC balance and dynamics. Actually the 19's amazed me at the dealers with their naturalness and engaging listenability.