I've decided I don't like the sound of my Roland KC-350s anymore. Not hi-fi enough. 
 
I have used small powered PA speakers in the past (JBL Eons) and they did a fine job on keyboards. Those have 15" speakers in them, which are a little weak in the upper mids so I'm looking for 12" speakers.
 
12 inches seems about right for keyboards, which I roll off the low end anyway to avoid stepping on the bass guitar. It's that or duct-tape my left hand to my knee, because I can't seem to play without that left hand joining in.
 
Top of my short list ATM is the QSC K12. Because they're ABS rather than wood, they're 8 lb lighter than my Rolands, which my back will appreciate. They're more powerful and take up less floor space.
 
On paper they look great. But I'm wondering if anyone here has used them for keyboard amplification. Or any other application that needs full-spectrum sound, such as a DJ or an acoustical band.

QSC seem to be the overwhelming speaker of choice for acoustic and keyboard amplification among the engineers I know.  It is a very good sound compared to the mackie and JBL monitors I have used, but not quite as good as the Yamaha DXR series I IMHO.  I usually rent a pair of K8's for my gigs when sound reinforcement is needed, and they fill very large rooms with full sound easily.  I think a K12 would be overkill for a keyboard and is better suited to large outdoor amplification.  

Firstly Dave are you talking one or two speakers here. Personally I prefer keyboard stage systems to have two speakers not one. Apart from the stereo it is also better for other band members as well. Not so much needed in the foldback but the stereo pair can usually take care of it live on stage.
 
Daniel may be right though. 1000W per speaker is a lot. I would be looking for a pair of speakers that are say 400 to 500 Watts a side and they will be physically smaller.
 
And while some brands may be slightly superior in quality I think in a keyboard stage rig in the din of the band on stage and all you won’t notice it too much. Hence the reason you could go Yamaha or quite a wide variety of other powered speakers. The market is pretty full of powered speakers right now.  If you are auditioning just take a great reference CD and have a good listen.
 
For example I recently heard a pair of Turbosound speakers and they blew everything I have ever heard in a powered speaker away but this is more listening to super quality full range material out front. But they are heavy and super powerful too and probably not that suitable for a keyboard stage rig either. eg overkill.
 
Maybe things like this:
 
http://www.sweetwater.com/store/detail/DBR12
 
Although this is rated at 1000W too.  But lots of power won’t go astray either. Nice to have the headroom there.
 
http://www.sweetwater.com/store/detail/ZLX12p
 
Try and find something that is smaller and lighter you will be thankful in the end.
 
 
 
 
 

I use a pair of K12s for my live show. Full SPlat backing tracks and live vocals. They fill big venues. I only need subs for those very large gigs. The 12" drivers are deceptively good at reproducing the low end when used with the DEEP button.
I do a couple of tracks just with solo vox and live VST piano and the sound is very good - crisp highs and accurate bass end.

Thanks for the feedback! 
 
Yes, I'm talking about using two of them. That's what I do now, setting one amp on either side of the drums. The KC-350s have a stereo link so I only have to plug my instruments into whichever amp is closest. None of the small PAs offer this feature, so I'll need some long signal cables. And a mixer.
 
Jeff, I was just looking at those Turbosound speakers (the iQ12) but was put off by their B.S. claim of 2500W of power. At 46.4 lb they're pretty heavy. Plus they're tainted by having the same parent company as Behringer. Still, they're $200 less than the QSCs so that's a plus. The Yamahas you suggested are also on my list, being cheaper and lighter than the QSCs. Plus I've heard them before and they sound fine.
 
The EVs were not on my radar, though, so thanks for that link.
 
As for 1000W a side being overkill, that may indeed be true (assuming those numbers are honest), but having headroom never hurts. Heck, I've got 800W on my frickin' studio monitors! I'll tell you what does hurt, though, and that's lifting those Rolands into the van at 2:00 AM. The Yamahas are considerably lighter than my current amplifiers.
 
Sir William, are you doing a solo act with the K-12's? That does seem like overkill. But encouraging. I have two musical enterprises, a 5-piece rock and blues band that gets pretty loud, and a quiet duo that never gets loud. Sounds like the K-12s might fit both situations well. 
 
The KC-350s have a 4-channel stereo mixer built in, alleviating the need for a separate mixer. Which also means I'll have to get a small mixer. That choice is easy, as I'm going with my favorite small-mixer brand, Yamaha. This one's bare-bones but has all the features I need.

 

Hi bitflipper. Yes, I do a solo show with them and find that the 1000w is about right to reproduce the full spectrum of being frequencies. Only in really large venues (400+) do I couple them with subs.

Well, it looks like the KC-350s are going on Craigslist. They're only 6 months old, so hopefully I can get $800 for them (they cost $1100). Then all I need to figure out is where the remaining $1000 is coming from...let's see, at $50 per gig that's only 20 Saturday nights.