i am trying out the little ATC SCM 11 with my Pass Labs Xa 100.8 .sounds wonderful.  Cannot get any other ATC speaker for demo.
wonder whether bigger ATC with my Pass Labs would sound better than ATC active as my amp is really very special
There really is no comparison the larger ATC SCM 19 are better in every way. We have voth the 11 and the 19 on display.

The 19 have a bigger soundstage, deeper bass, greater clarity in the midrange, they are shockingly good and would sound fantastic on your amp

Troy resident geek, Dave owner
Audio Doctor 
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I too had the 11’s for a week and decided to go the 19’s...was very impressed with the 11’s and in my room they would have worked wonderfully...but stepping up to the 19’s/sound anchor’ the pro driver and just everything is just a another level...highly recommend...oh and i would have always wanted and wondered about 19’s if i had the 11’s...With your amp...would think quite pleased.

I think the biggest advantage of an active powered speaker is there is none of the mismatching of components to the "perfect" match...and yes that is very desirable...but I do think the passives are amazing as well...with jazz and well recorded material...I placed them no diffraction (straight at me) after a day moving them around the room....friend came over to have a listen and said "im tripping" his system is thousands! of dollars over my system...well matched and well placed in your listening room...if you like the 11’s...19’s are guaranteed to please you...

Sweetwater does carry the active/scm 20 for 5k...fwiw

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Very different that hasn’t been discussed, is the active has better sharper active (-24db) xover slopes compared to the passives (12db-18db), which means the drivers are working in a better part of their frequency range, should equal less distortions. Not because of the muti amps, but because of the active xover. But then there's the sound of the active xovers to consider with all their electronics now in the signal path. 

Cheers George
"..but stepping up to the 19’s/sound anchor’ the pro driver.."

pro driver? i do not see this driver on the 19
They are the same as scm 20 which is pro monitor...they should show pic on atc web site
I noticed a pair of ATCs at Goodwin's recently and the grills looked like chicken wire…not in a bad way...
Wolf garcia,

Yes the grills do look like like crap, the speakers are insanely great.

The whole concept with ATC is the money goes  into  the drivers, the cabinets are workman like, not about beauty of the wood work, the cabinets are designed to be rigid and purposeful. 

If you compare the size of the woofers magnet and the design of their drivers and their superb crossover, that is why they do what they do.

I would  take a pair of ATC 11 or 19 over a lot more expensive speakers, if you dare to compare them to many of the top audiophile brands the ATC just sound more life like, with startling dynamics.

A snare drum sounds like a real snare drum, same with a kick drum. The vocals have  a silky naturalness and the images are gigantic and very holographic. 

Audio Doctor old website new one comming
877 428 2873
With ATC you are buying excellent drivers and superb crossover,they do not care much about beuty design .This company has a very professional approach to their speakers.
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Definitely with grills off...doesnt seem like it would make that much difference....but i surely does.
ATC active is most important for their three ways. In a two way you could go either way (passive or active) with great results provided the passive amp is beefy (at least 150 watts on the SCM 20).
First, I think chicken wire speaker grills are fine as they do keep chickens from damaging the drivers, which can be a nightmare…so there’s that. Also, by utilizing active speakers of any kind (yeah, I recently read the ATC review in the Absolutist Sounders) you wind up with amps that just sit there and do nothing. Collect dust..sad…*sniff*...My beef with active stuff has been mostly related to active P.A. gear which obviates my ability to Field Repair things (although that has rarely happened), and I’m seriously changing my mind about that anyway since working with computerized sound systems allowing a "musician specific mix" for monitoring using powered boxes…each person on stage can get their own independent mix in any Also, active home gear means you can’t mess around with various amps and tubes and wires…what’s the fun in that? Sure, the active ATCs may sound better, but really, deny my right to waste time and money on amp stuff for Better Sound? No way man...

Agreed modwright kwi 200 has 200 watts aside...really would like to kick it up to three hundred and see what kind o sh"tuff" happens...

Got to believe these thing's would just start to tighten there belt...they do love the power...

Agreed wolf...that would be limiting...sure they would sound great would be nice to choose...

There could be a revolt among "stand alone" amp designers…imagine over half a dozen angry amp techs marching on Washington. 
I am a Pass Labs lifetime customer, but I too was enticed by the active atc story.  the amps are a-b not class a like pass so not as liquid sounding.
I had the 15" actiive three ways (5 years ago or so).  it was impressive in many ways but the integration of the drivers just seemed off a bit.  Maybe the newer ones are better.  I bought mine used and sold them in 6 months for what I paid for them so it was a nice adventure.  I would have to say that looking at the amps ( I took them apart) i wasn't impressed by the build quality.  Just the clutter, soldering wires etc. struck me as a bit dated.  I went back to Pass and passive speakers. Pass is known for really clean designs so maybe I am spoiiled.  But the active thing makes a hell of a lot of sense.  Even Nelson Pass made a big active speaker.......few bought it though...........

I believe ATC actives are biased Class A to 2/3 power. So they are Class A for the most part.

They are dated - discrete components and easy to repair and only minor tweaks over 30 years. Part of the appeal is that ATC got it right from the beginning. 

Unusual that the driver integration did not work for you - maybe your used speakers needed servicing.
Do they make a lot of heat? Do you leave them on all the time or only turn them on when you want to listen to music? Do they have a long warm-up time?
I turn them on just for music - I have not noticed a warm up period but it would take an hour or so to fully warm the massive heat sinks. They do run warm but nowhere near as hot as a Bryston 4B SST just idling (Class AB). Each amp drives only one transducer over a narrow range of frequencies and I believe the active version has a 16 ohm version of their mid range driver - so power is not excessive and heat is quite modest. There are no passve crossovers so all the power of the amp reaches the voice coil.
Hi everyone
Just joined Audiogon.  I've been importing ATC to the US for almost 20 years in pro, just started in Hi FI and few years ago.  Just saw this thread.

The real advantage of active is a practical one from the ATC engineering perspective.
The problems are 
1) losses of a passive crossover, power losses of speaker wire, dampening factor issues with length of speaker wire, etc. 
2) no precise phase adjustment of drivers in a passive crossover design.  
3) as drivers heat up, values of the drivers change and the passive crossover sees a changing load, therefore changing crossover behavior
4) Two well designed 3 ch amps and power supplies within the speakers can be built for less than a large two channel amplifier with pretty chassis, case and feature set and all the connecting cable.  

Brad Lunde
Lone Mountain Audio