Well, I guess I'm going to be the one to contradict others views on Behringer. I have a K1800FX and love it. I also have a JBL EON-15G2, a pair of LEM D400's and a Leslie 3300, 122 and 145. Until recently I had a Traynor K4. I sold it because of the absence of any low end to speak of, non-existent stereo imaging due in part to both left and right speakers being mounted on the same plane instead of being angled away from each other and the fact that I believe the crossover point is set to low sending too much mid to low-midrange signal to the summed woofer. Other than that it is a great amp; I used it along with a Motion Sound SW15 powered sub, which I still have. Prior to the Traynor K4 I had a Motion Sound KP200S which had better stereo separation than the K4 but didn't compare in features and sound.

Last year I needed a smaller amp for various gigs. I ended up with the Behringer after comparing it to the offerings of Roland, Hartke and Peavey. The K1800FX had better features than the others, cost less and sounded just as good (they all sounded a little different from each other side by side but all sounded good). I have used the K1800FX quite a bit and have never had a problem with it. I'm glad I chose the Behringer.

added- If you are considering the KC550 from Roland, check out the Behringer k3000FX. I have used bass pedals with my K1800FX and it worked pretty well, but the extra power and 15" woofer of the K3000FX would pump out more than enough bass.