If the amp watts is rated @8ohms, then if your speaker is lower impedance, it will request more watts from the amp. Double in ideal amp if going to 4ohm.Thanks @Garman, I agree more wpc doesn't mean better sound. I have tested both Atom and M10 with Special 40 and I wasn't satisfied with what I heard...maybe because I also heard XS3 or Pier Audio with them.
I am not sure I understand your statement "But looking at the Special 40 being at 6 ohms that something with more juice is in order." What does 6 ohms means and how that plays with the amplification?
This can be ‘uncomfortable’ for the amp resulting in clipping or overheat. Mostly only account for volume going to wide open.
More important i think, you require a bit more juicy amp, is the low sensitivity of the special 40 ( 86db) but measured even lower by reviewers.