Maybe it's just a case of subjective difference in how much of a change it makes? I wasn't seeking much bass increase (in impact or quantity) in the first place, may make some kind of bias. The bass boost made a bigger difference. However, your comment does make me interested in the ALO National, how much $$ do those run for?
They run $299 MSRP.
FWIW - The M100's are very efficient for full size headphones so it doesnt take a ton of power to drive them (unlike planar magnetic headphones). Given that, the cleaner the amp is the better. I wasnt happy with The National and my Mad Dogs because they didnt have enough power for them, but it was flat out awesome with my M100's.