It won't. If you don't need more channels of amplification and you aren't clipping (and are controlling and driving your speakers to their best on the channels you have), then adding amplification is wasting money.
Volume is seldom the issue for moving to a monoblock design as the actual gain in volume is slight. 100 watts changed to 200 watts, everything equal, is only going to add 3dB which is barely noticeable on music content. Total separation of the channels is more often the desire. The benefit you might derive is somewhat dependent on your speakers and the load they present to the amplifier. By strapping the Krell into mono it may be more suited to dealing with the dynamics of the music. You should notice a gain in soundstaging and imaging if you have already tweaked the system to get the best from all the components. If you have not explored the gains made in other areas of your system, however, adding the amp is less likely to show the most benefits. The simple answer is try it and decide for yourself. You have not given enough information in your request for anyone out here to really help you.