ATC SCM 40 vs. ATC SCM 50


Has anyone compared these two models?
I've heard SCM40 and I've been imporessed! So I'm interested in the bigger ones because they are in my budget for spekers. They cost much more and they are from the Tower series which is the highest line of ATC spekers so they must be even better than the wonderful SCM40.
Any opinions? :)
julianj
A question @ the powered ATC's... with three amps in a speaker (6 total for a pair) what are the power requirements to operate all of those amps . For instance , I have dedicated 20 amp circuits for my audio pieces . But the speaker placement would not allow the use of these circuits . They would have to use standard home 15/20 amp circuits that are being used by other household items as well .
Hi guys, i'm considering SCM 50 passive as a second pair of speakers to have something with different qualities than the other speakers i'm considering the Borresen 03s.I need an amp that will drive both to their max.Would the Audionet Humboldt be awsome on the SCM 50 ?
I run the ATC SCM 40 active tower and they are formidable in respect to slam, resolution, soundstage and attack.  This a speaker that lives on immediacy.  Surprising bass and dynamics for a 6.5” bass driver in a sealed cabinet.  Very controlled.  

I would pass on the passive ATC models.  Not because they are bad, it’s just that the investment in quality frontend and high current amplification becomes enormous when all of the amplification work has been done properly by ATC.