Hi, Alberto. Incidentally, a friend is solliciting amplification opinion for his EA II. Is your thread a question, or a suggestion?
I listened to EA II driven by Krell 100, YBA Passion, and Symphonic Line RG7 -- but not your KSA 50s. Pre and source were YBA. Cabling was ART and bearlabs. To my ears, the YBA gave the most (musically) involving results -- it made the amators "come alive" if you will. The RG7 came a close 2nd. By comparison, the sound through that particular Krell lacked vitality -- it probably didn't synergise with the speakers, the pre, or all; I cannot say.
BTW, SF offer own-brand electronics too. You may want to check those out as well.