I have gone direct line outs into my K10’s for a few years now. Works like a charm…

But I do carry a little mini mixer (Yamaha MG06X) in my cable case, just in case I either have someone want to sit in, or the venue wants a feed for the house, or I need something to convert to mic level from line level (which saves me from carrying a DI box as well). It’s a very versatile mixer, and allowed me to have a three piece with no extra gear (two other singers, one who played guitar).

The only issue with needing a mixer for some people is if a) your keyboard doesn’t have a mic in with EQ and effects, and b) if your PA only has XLR inputs and your keyboard only has line level 1/4” outputs and you don’t have a D/I box.

Keyboards have a fairly hot line level output, so the odds of you running into a PA that your keyboard’s volume knob was incapable of getting to full power (before distortion!) are slim to none…

So, bottom line, you don’t NEED a mixer if your keyboard has a versatile mic in. But it is handy to have a small one like mine as an audio toolbox just in case! 🎹😎