ATC active vs. passive

I'm leaning toward 150 passives. Part of this hobby is constantly playing and tweaking with components. 

What tube amp would pair well with ATC?  I'm open to integrated as well. I doubt my current 50 and 100W tube amps will do justice on 150. 

I heard the Mcintosh hybrid amps are too slow for ATC. 

I love tube amplification and worried that if I get an active model I may not achieve the tube sound. I read that active amplification is superior for multiple reasons but would that trump the benefits of tubes? Would I regret actives in the long run? 
would it be possible to easily convert active to passive ?

@lonemountain 

appreciate the detailed response

1. I have a big room, 45 x 15 ft

2. listen to classical, piano and large scale orchestra at high volume 

3. absolutely love tube sound and have the ability to bi amp a passive system if needed. I enjoy the harmonics that tubes bring 

4. I value accurate tone and timbre of musical instruments, especially cello piano and violin. 
 

5. I have an all analog system with TT and tube everything in the chain 

knowing all this, would you still recommend an active over passive ? 
in what situations would passive be recommended? 
 

Thanks 

I'm interested in 50 and above. Where can I demo those in NY/NJ/MA/CT area? 

My tube amp is Auris fortissimo, 100W Push pull. 
I’m concerned it wouldn’t be enough to power SCM150 that I’m considering. 
I have a big room, I like to listen at high volume. I am in the position to buy anything ranging from 50 to 150 both passive and active. I’m trying to make the right decision 

@lonemountain 

Thanks for your input. 
“The active system exhibited much bette imaging and better high resolution of fine details like room sound, reverb tails, harmonics on piano, acoustic guitar, violins. ”

I understand what you said above. I recently auditioned Wilson XVX and I was blown away with every metric that audiophiles find valuable. It was the most powerful, transparent, detailed with perfect accuracy and imaging that I’ve ever encountered. However, it was not enjoyable engaging or musical. It was analytical and clinical. That isn’t what I want. That’s why I’m entranced by tubes. The beautiful sweet sound with rich harmonics is that I’m after. I’m used to high powered SET sound  

would you still recommend actives for my taste ? 

@lonemountain 

1. is it possible to self modify Active into passive down the line if get tired of active and would like to try other amps ?  Is it possible to purchase passive crossover and swap them at home? 

2. 150 is considerably wider baffle than 50. How does this affect the imaging and the ability to disappear. Logically, 150s should be much harder to disappear 

There isn’t a single dealer in the northeast that has ATC SCM50 or higher.
I’ve auditioned most other brands ranging from 10-300k, none of them had the dynamics, timbre and accuracy of ATC except Avalon acoustics Saga. Those are the very best I’ve heard but the price is out of reach. 

I bought ATC scm40 and powering them with luxman 595, MASTERSOUND 845 and Grandinote Shainai integrated amp. 
I like the tonality and happy with low end. However, the tweeter is inferior to my Triangle Magellans. I’m still interested in ATC 50 and 150, hoping the tweeter is a big upgrade from the 40. 
if I get the 150, I probably won’t have enough to upgrade my amp for a while. Hopefully luxman 595 is enough. 

I have the scm40 MK2 version. Still lacking to my ears compared to Triangle Magellan. I know ATC SCM50 and above have a superior tweeter just not sure how much of an upgrade it will be. 

Speaker cables : 

1. analysis plus solo crystal oval 8 

2. nordost hemidal 2

power cord 

1. Analysis plus  Ultimate power oval 

2 analysis plus power oval 10 

stock jumpers 

scm40 has 500h

@dpac996

your statement about my amps matches my observation exactly as you predicted

GrandiNote and MasterSound ran out of steam very quickly, I had to max out GN volume to 100% and it was barely adequate

same with MASTERSOUND, beautiful midrange and highs but absent low end

luxman by far the most powerful and I am using it exclusively. 
 

I also have Auris fortissimo tube amp which is 100W, but 595 sounds better 

Which tube amp do you think would do justice to scm150?