Hello! Can you advice where to install CDT 5800-C II speakers in ceiling for my Marantz SR 7011 receiver? My media room dimension is 15ftx18ft with 10ft ceiliing. I have four of these. Thinking whether to go with 2 speakers or 4 speakers. Can you advice if I install only 2 speakers where to place and if I install 4 speakers where to place them?