ATC SCM150 Amp and Preamp recommendations

@erice64 Did you mean the ATC SCA2?

If so, I would agree, especially with the actives. Often synergy between like brands trumps everything else.

@vinylvalet yes I do. The SC-2 drives an ARC 250 to Magico S5, simply lovely😁 Also the preamp has a low output impedance especially for driving the active speakers, hence the synergy. Guess thats also the reason why my tube amp is driven with ease and force.

I am the US importer.  The actives will outperform the passives every time, not due to amplifier issues but do to control of phase.  There is no way to control phase in a passive crossover.  This a huge performance issue very few talk about. 

In a passive, a well built crossover has a TON of wire in between amplifier and drivers.  There could be hundreds of feet, especially in air core inductors.  I don't see in any scenario how that could be an improvement over hooking the amp directly to the driver with 1 foot of wire.

Next the ability to calibrate each amp precisely to the driver itself (efficiency of a completed drive unit can vary in the very best of the best manufacturing from 1/4 to 1/2 dB.  1/4 to 1/2 dB across an entire band is very audible.   .    

Next is the ability to sustain large bass dynamics while not affecting the top end HF amp or Midrange amp in any way.  A full range amp cannot do this, as the bass running the amp out of power is well understood.  The way most of us get around the obvious there is through massive OVER power delivered at the speakers, accounting for the loss of power and reduction of dampening factor down as little as 10 feet of cable.  Linear analog amps seem better at this as they have larger reserves inside a power supply.  The why ATC's own amps are class A/B and have a large linear power supply.

Maybe look at trying an ATC P2, which is 300W /channel as a first step.  that will tell you if it's enough and you need the Titan.  Keep in mind a 800w amp vs 300w amp is only about 3-4dB of average level increase.  At 110dB SPL, 3 db more SPL is a small amount.  DO the math on the 150s and see how loud 300W will be.  

Active ATC 150s will play at around 115dB or so long term, depending on dynamic range of the source.  I cannot listen that loud and I ve never run into a hi fi customer that does.  Most people cannot get much over 105dB SPL before they start freaking out.  The 95dB SPL is LOUD, and the 115dB SPL capability (20dB of reserve) is for peaks.     

Is this helpful?  I would think a 300W amp on passive 150s would make one very happy and allow some money to buy a great preamp and a great DAC, Streamer etc.

Brad

Lone Mountain Audio (ATC Hi FI USA)

TransAudio Group (ATC PRO USA) 

 

@lonemountain 

Hi Brad,

 

Thank you for the detailed and thoughtful response. I appreciate your insight as the U.S. importer and certainly respect ATC’s engineering philosophy—especially the precision and integration of their active systems. The technical points about phase coherence, component tolerances, and amp-driver calibration are well taken and valid from a design purity standpoint.

 

That said, I chose the SCM150 passives very deliberately, not as a compromise, but because they allow me to shape the sonic outcome exactly as I want it. My priority is extracting a harmonically rich, dynamic, and lifelike presentation—qualities I’ve been able to enhance by pairing them with an ultra-high-current Class AB amplifier and a well-matched tube preamp. The transient performance and low-end authority I’m getting now are exactly what I was seeking.

 

While I understand the argument about passive crossovers and inductor wire lengths, in practice, the performance delta depends heavily on system synergy and listener priorities. The subjective gains I’ve achieved through amplification choice—particularly in tone density and spatial realism—outweigh the theoretical drawbacks of the passive network in my setup.

 

Regarding power: you’re right that +3 dB isn’t a night-and-day difference on paper, but in dynamic music like large-scale orchestral works, the added headroom of an 800W+ amp translates to more effortless macro- and microdynamics at live-like levels, especially with complex low-frequency content. For me, it’s not about listening at 115 dB, but about having total control and composure when the music demands it.

 

Ultimately, this comes down to different paths to musical satisfaction. I fully understand the merits of the active approach, but I’ve found that the passive route—with the right amplification—gives me the flexibility and sonic character I value most.

 

I sincerely appreciate the dialogue and hope we can stay in touch as I continue refining the system.

 

Rotel Mitchi M8 is a nuclear weapon when it comes to power. Stereophile has a review on these monos. I have heard the stereo version of the M8.