I have a pair of Roland KC100. The reason I selected the KC100 is because I sometimes have to perform at churches seating 300+ people. So KC100 was able to deliver the power I need and it is relatively small for the amount of power you get from them. But as George said the pair will cost you over $500.

What do I think of the sound quality? Good but not great. When I listen to sk880 through different headphones, the quality of the sound is better. There are two possibilities:

1) KC100 is flat and realistic Headphones are enhancing some of the frequency.
2) Headphones are more realistic so you are losing some "middle and low" frequency from KC100.

I tend to believe that #2 is the right choice. However, today I will be listening to the Keyboard through Event PS6 biamplified monitors and I will test that theory further.