any experience with Pipedream 21 s ?

I am getting the 21 s very soon. Two sub cabinets rather than four are included. Any real world experiences that can help me prepare for their arrival would be of enormous help. I have the Classe Omega amp/ pre combo on Nordost spms at this time. Bat vkd-5se cd . Very high ceilings open to a large great room with angled walls everywhere. Where do I sit in relation to width which will be most likely 8-9 feet apart. Can only be 4 feet from back wall however. Any suggestions that may help? Also I need advice on a sub amp. Thanks in advance, brent rainwater.