Jay. The Martin Logan Motion 40 has crossovers at 500 and 2600.
Little woofers struggle to make deep bass. They have to make long excursions causing distortion at all other frequencies. Middle C is 256 Hz so those woofers are carrying a large chunk of the midrange, over an octave. Instead of another amp I think you would make a more significant improvement if you get two subwoofers. They will add the missing deep bass and if you use a full 2 way crossover on them they will relieve thos little woofers from those long excursions cleaning up your midrange significantly.
Otherwise you can not go wrong with The Parasound A21+
Little woofers struggle to make deep bass. They have to make long excursions causing distortion at all other frequencies. Middle C is 256 Hz so those woofers are carrying a large chunk of the midrange, over an octave. Instead of another amp I think you would make a more significant improvement if you get two subwoofers. They will add the missing deep bass and if you use a full 2 way crossover on them they will relieve thos little woofers from those long excursions cleaning up your midrange significantly.
Otherwise you can not go wrong with The Parasound A21+