Morph...
I don't know what to tell you. The single 15" I'm playing thru for both keyboards, handles the highs and the lows just fine. The high end brass (trumpets) come through nice & bright when needed. The bottom ends, including trombones, susa's etc. have got great presence. It also handles any piano work just as well, in addition to whatever organ ie.(B3) I'm replicating. But as I said, it's basically an on stage monitor (from behind) just to give me that "push" on stage, it's routed through our front end by both mic, and line out, where our soundman does his magic from there.
Just my thots.