In my case the bass response improved not by replacing speakers, but with a new set of amps! Getting a good performing amp is very important to get the most out of the speakers. I was so satisfied with the bass performance I even got rid of the Velodyne DD-12 subwoofer that I was using.
Short List of the Best 20K Speakers
I'm looking to pickup a pair of pre-owned speakers that originally sold in the twenty thousand dollar range and can be had for around half that today. I currently own Revel Studios. I love them but want something that can go below 20 hz while still maintaining all the goodness these speakers provide. I've already heard and liked Dynaudio C4, Revel Ultima Salons (original) and Eggleston Andra II's. It's hard to get a real feel for what they sound like in your home with your equipment. Curious to hear from people who have owned or auditioned any of these. Also feel free to add any you would like to recommend. My amp is a Krell FPB600c. My room is unfortunately a 20' square with 8' ceilings. I have echobusters placed all over to keep the soundwaves from pretending to be pinballs in a pinball machine.