I just contacted the Tom at SVS. I just bought a velodyne ct10 and I have it in a room that is 20'x18'. It just does not produce enought bass unless you turn it way up over the volume of everything else. I want the base you can feel. What are you opinions? Tom suggested the 20-39 and the samson s-700 amp. Would I notice a big difference. Tom stated that the 20-39 has 50-67% more clean output capability compared to a velodyne ct-15!!!!!!!!Wow! I still have time to return the velodyne. Thanks very much!!!