the conclusion of guy here was :
"For me, my musical tastes and my system, the higher output and more dynamic AT-ART9XI was the best fit. However, if you have some gain in your phono preamp and your listening tastes tend more to the acoustic and classical end of the spectrum, the AT-ART9XA could be an excellent choice."
since i am listening to a variety kinds of music, rock, jazz, classical, that's increase my dilemma.