Guys @lanx0003 @digsmithd thanks for your insight and sharing. FYI, i just sold my 200W Krell KAV-400xi amp after moving to small room, otherwise it should easily drive SCM7.
I have asked ATC distributor, they said E280 (damping factor 500) able to drive this speaker. Just my little concern on lower bass frequency especially double bass or equivalent instruments may be hard to be auditioned