ATC SCM 40 vs. ATC SCM 50

I prefer the passive. I won't miss the pleasure of trying different amps. :)

No problem - but consider that you can still play with your source and preamps (tubes etc). ATC built in power amps run class A to two-thirds power - three amps per speaker - something you will find hard to achieve in a powerful but separate class A power amp.

Shadorne, I hadn't thought about the amps in ATCs that much. If they run Class A... does the speaker enclosure throw off a lot of heat?

Shadorne, I hadn't thought about the amps in ATCs that much. If they run Class A... does the speaker enclosure throw off a lot of heat?

A fair amount (as much when they are idle as when you run them hard) but remember that the amplifier does not have to power a lossy passive crossover or handle large impedance swings - since it is band limited to only the frequencies necessary for the particular driver. This allows for much greater efficiency and optimization.

Concur with Shadorne. I have had the 7, 11, 19 and 150s. Across the board, great speakers.

Cost no object, ATC SCM 50 is the choice. This is because SCM 50 uses the audio grade dome midrange (part number SM75-150s) while SCM 40 uses the public address grade dome midrange (part number SM75-150). That's explained the difference in price and sound quality.

Hope this helps.