Lets get back to the subject at hand. You are trying to push a musical instrument through a pair of speakers that were not intended for that use. I workout on a set of ROLAND V DRUMS and use the recommended amplifier, KC 100, KC 300, KC 500 are recommened. I use two KC 500 units. It just doesn't get any better than that.
This series is manufactured by ROLAND for use with KEYBOARDS as well as PERCUSSION SAMPLING UNITS. Give them an audition, you might like them

Jim / CAV104