When you say power speaker, basically what you're referring to is a "powered speaker" cabinet, with which there is generally not a lot of control. and a separate speaker is going to need power from some place...ie: power amp..that being said, for what your looking at doing, (and I know I'm gonna get flack over this) is why not look at a 50 or 80 watt keyboard amp, with a 15".
A lot of the members here will disagree with the 15" aspect. These are my own personal preferences. I find the 15 has more punch for the bottom ends of a kb. Just because the amp is 50 or 80 or 800, that doesn't mean you have to crank it to 11 and start blowing out windows. The power is there if you need it, but run through a pedal for control, so you'll have that headroom when you need it. I've got a punchy little Fender 112 Deluxe (90 watt) which I use for guitar, and it's great...but...when I run keys through it...."it's horrible". The 12" just doesn't have the ..ooomph..I need. Talk to one of the techs in your local music outlet and see what they have to say.
Good Luck
Have a look...
http://www.yorkville.com/products.asp?type=32&cat=16&id=86

------------------
...L


[This message has been edited by shboom (edited 12-15-2004).]