You replace the VR7's with something else and you still are going to have the problem w/o the DD18. I don't see how changing the main speakers will do anything other than change the amount/frequency of energy the DD18 has to add to overcome the bass deficiency. What are you trying to accomplish; it is unclear to me?
Speakers to alleviate room anomolies
I have a suckout of 8db from 58 -70 hertz which is taking the life out of the music. I currently have Von Schweikert VR7SE an added a velodyne dd18 which took away the problem. It gave the bass energy in my room of 30 x20x10. It seems I do not need the big cabinet speakers[VR7SE] if the woofers aren't throughing enough. Speakers with active woofers like the evolution acoustics mm2 have been recommended. Any other ideas of speakers in conjunction with the velodyne dd18 to make my room sing again.