@luis, what minimum wattage should one strive for,Considering the cost...
my actual experience, minimum:
tube 22 wpc triode / 45 wpc ultralinear
solid state a-b amplification 80 wpc
solid state class a 40 wpc
however, audition first to check the matching or pairing of amp and speaker. after which, decide if you need higher wattage or not. higher wattage means more juice for the speaker means can do higher volume. higher wattage means better SQ, I AM NOT SURE.