Any amp that can give good current drive in these loads from 20hz to 20khz and stay flat with it's frequency response would be the amp to consider (look at the bottom of the page for the impedance graph in the link)
The CLX range from 100ohms in the low bass (which most amps have no problem with) to very low impedance through the upper bass/midrange, and extremely low impedance through the high frequencies.
The amp to get is an amp that has good wattage into 8ohms, because the CLX's are not too efficient at 84db, but ones that can increase their wattage for each halving of impedance down to 2ohms, these amps will give you nice linear drive (stay flat) from 20hz to 20khz. Some tube amps are ok but they need a 4ohm tap and have low output impedance < less than 1ohm, preferably .5ohm
Amps that cannot do this may still sound ok, but will not produce a flat response, they will act like a fixed tone control, up in the bass and down in the treble.http://www.hi-fiworld.co.uk/loudspeakers/65-reviews/252-martin-logan-clx.html?showall=1